Emu Hojo

Emu Hojo (宝生 永夢, Hōjō Emu), also known by his gaming tag of "Genius Gamer M" (天才ゲーマーM, Tensai Gēmā Emu), is a master gamer and pediatrics intern, later surgical intern, who had been inspired to become both after receiving a life-saving surgery and a WonderSwan handheld console from Kyotaro Hinata. Emu is well-meaning and friendly, but also clumsy and absent-minded, which often gets him into trouble with nurses. As the series progresses, however, he matures and becomes less naive, picks up Kiriya Kujo's lying habit, and becomes a master manipulator comparable to Kuroto and Masamune Dan.

Sixteen years prior to the series, the antisocial Emu had found solace in designing game characters. After sending his concepts to Genm Corp. game designer, Kuroto, Emu received a prototype game that infected him with and turned him into patient zero for the Bugster Virus. As a result, an alternate persona called Parad manifested from Emu's desire for a playmate and assumed control, leading to the latter becoming "M" and being kidnapped by Next Genome scientists who had sought to extract the Bugster Virus for Kuroto. However, Parad had turned into a Bugster and separated himself from Emu, allowing the latter to pursue his desire to become a doctor and earn an internship at Seito University Hospital. Despite being separated from Parad, trace amounts of the Bugster's data causes Emu to maintain his gamer persona, become a Kamen Rider, and later grant him the ability to create Gashats from his imagination. After being recruited by CR, Emu has several encounters with Parad, discovers what had happened to him, and joins forces with Parad and other Gamer Riders to defeat the Bugsters and Masamune.

Utilizing the Gamer Driver in conjunction with the platform game-themed Mighty Action X (マイティアクションX, Maiti Akushon Ekkusu) Gashat, Emu can transform into Kamen Rider Ex-Aid Action Gamer (アクションゲーマー, Akushon Gēmā) Level 1. In this form, he gains increased agility and can transform further into Action Gamer Level 2. In both forms, he wields the Gashacon Breaker (ガシャコンブレイカー, Gashakon Bureikā), which can switch between Hammer Mode (ハンマーモード, Hanmā Mōdo) and Blade Mode (ブレードモード, Burēdo Mōdo). Additionally, activating Mighty Action X generates a Game Area (ゲームエリア, Gēmu Eria) digital field and several Energy Item (エナジーアイテム, Enajī Aitemu) medals with unique power-ups randomly hidden inside chocolate block-like containers that he can use for increased traversal capability. Moreover, he can combine Mighty Action X with additional Gashats to achieve stronger forms, which are as follows:

• Robot Action Gamer Level 3 (ロボットアクションゲーマーレベル3, Robotto Akushon Gēmā Reberu Surī): A form accessed from Mighty Action X and the beat 'em up-themed Gekitotsu Robots (ゲキトツロボッツ, Gekitotsu Robottsu, Clash Robots) Gashat that equips him with the rocket-powered Gekitotsu Smasher (ゲキトツスマッシャー, Gekitotsu Sumasshā) gauntlet.
• Hunter Action Gamer Level 5 (Dragon Fang) (ハンターアクションゲーマーレベル5 (ドラゴンファング), Hantā Akushon Gēmā Reberu Faibu [Doragon Fangu]): A form accessed from Mighty Action X and the multiplayer game-themed Drago Knight Hunter Z (ドラゴナイトハンターZ, Dorago Naito Hantā Zetto) Gashat along with one to three other Gamer Riders that equips him with the Horn Drago Helm (ホーンドラゴヘルム, Hōn Dorago Herumu) headgear and the extendable Whip Drago Tail (ウィップドラゴテイル, Wippu Dorago Teiru).
  • Hunter Action Gamer Level 5 (Full Dragon) (ハンターアクションゲーマーレベル5 (フルドラゴン), Hantā Akushon Gēmā Reberu Faibu (Furu Doragon)): A stronger variant form that equips him with the Drago Knight Blade and Gun along with his original weapons.
• Burger Action Gamer Level 4 (バーガーアクションゲーマーレベル4, Bāgā Akushon Gēmā Reberu Fō): A form accessed from Mighty Action X and the cooking video game-themed Ju Ju Burger (ジュージューバーガー, Jū Jū Bāgā, Sizzling Burger) Gashat that equips him with the roller skate-like DD Inliner (DDインライナー, Dī Dī Inrainā, Dash and Deliver) sabatons and the arm-mounted Redchap Launcher (レッドチャップランチャー, Reddochappu Ranchā) and Yellowstard Launcher (イエロースタードランチャー, Ierōsutādo Ranchā) condiment bottles.
• Pac Action Gamer (パックアクションゲーマー, Pakku Akushon Gēmā): A form accessed from Mighty Action X and the Pac-Man-themed Pac Adventure (パックアドベンチャー, Pakku Adobenchā) Gashat that equips him with the PAC Fight Glove (PACファイトグローブ, Pakku Gaito Gurōbu) gauntlets. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Gamer Stage.
• Bike Action Gamer Level 0 (バイクアクションゲーマーレベル0, Baiku Akushion Gēmā Reberu Zero): A form accessed from Mighty Action X and the Proto Bakusou Bike (Combi Fukkatsu Version) (プロト爆走バイク [コンビ復活バージョン], Puroto Bakusō Baiku [Konbi Fukkatsu Bājon], Proto Burnout Bike [Combi Revival Version]) Gashat that grants superhuman speed, and arms him with the Front and Rear Armed Units. This form appears exclusively in the Kamen Rider Lazer Hyper Battle DVD special.

If necessary, Emu can also use Genm's Gashats to assume different Level 3 forms:

• Sports Action Gamer Level 3: A form accessed from Mighty Action X and Shakariki Sports that arms him with the Trick Flywheels.

Additionally, Emu can achieve the following forms by utilizing unique Gashats in place of Mighty Action X:

• Double Action Gamer Level X (ダブルアクションゲーマーレベルX, Daburu Akushon Gēmā Reberu Ten/Ekkusu) and Level XX (レベルXX, Reberu Tuenti/Daburu Ekkusu): A chibi-like form and its subsequent sleeker upgrade, both of which are accessed from the double-sized co-op game-themed Mighty Brothers XX (マイティブラザーズXX, Maiti Burazāzu Daburu Ekkusu) Gashat. The latter form splits him into the azure-colored Double Action Gamer Level XX L, which represents Emu's level-headed doctor personality who prioritizes his patient's safety, and the orange-colored Double Action Gamer Level XX R, which represents Emu and Parad's hot-blooded gamer personality who prioritizes defeating his opponent and ensuring victory in battle. In this and all subsequent forms, Emu wields the Gashacon Key Slasher (ガシャコンキースラッシャー, Gashakon Kī Surasshā), which can switch between Blade Mode, Axe Mode (アックスモード, Akkusu Mōdo), and Gun Mode (ガンモード, Gan Mōdo) as well as utilize either two normal-sized Gashats or one double-sized Gashat to activate its Critical Finish. Double Action Gamer Level XX first appears in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider.
• Maximum Gamer Level 99 (マキシマムゲーマーレベル99, Makishimamu Gēmā Reberu Nainti Nain): A mecha-like form accessed from the double-sized mecha simulation game-themed Maximum Mighty X (マキシマムマイティX, Makishimamu Maiti Ekkusu) Gashat that automatically transforms him into his Action Gamer Level 2 form and grants the use of the Maximum Gama (マキシマムゲーマ, Makishimamu Gēma) armored suit capable of flying and extending its limbs, which Emu can separate from and leave on autopilot while maintaining his Level 99 power, the ability to rewrite a Bugster's coding, depower most Gamer Riders, and heal Game Disease victims. His finisher in this form is the Critical Break (クリティカルブレイク, Kuritikaru Bureiku).
  • Muteki Gamer (ムテキゲーマー, Muteki Gēmā): The evolved form of Maximum Gamer Level 99 accessed from the Maximum Mighty X Gashat combined with the cheat cartridge-like Hyper Muteki (ハイパームテキ, Haipā Muteki, Hyper Invincible) Gashat that grants warping capabilities, immunity to negative status effects, and a Save (セーブ, Sēbu) function that renders him and allies immune to Masamune's Reset ability. His finisher in this form is the Critical Sparking (クリティカルスパーキング, Kuritikaru Supākingu). If Hyper Muteki is combined with regular Gashats, it activates a Muteki Mode (ムテキモード, Muteki Mōdo), which grants temporary invincibility.
• Ghost Gamer (ゴーストゲーマー, Gōsuto Gēmā) Level 1 and 2: A chibi-like form and its subsequent sleeker upgrade, both of which are accessed from the Kaigan Ghost (カイガンゴースト, Kaigan Gōsuto, Eyes Open Ghost) Gashat that arms him with Kamen Rider Ghost's Gan Gun Saber. These forms appear exclusively in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider and the web-exclusive special Kamen Rider Genm: Legend Rider Stage.
• Drive Gamer (ドライブゲーマー, Doraibu Gēmā) Level 2: A form accessed from the Full Throttle Drive (フルスロットルドライブ, Furu Surottoru Doraibu) Gashat that arms him with Kamen Rider Drive's Handle-Ken. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Rider Stage.
• Gaim Gamer (ガイムゲーマー, Gaimu Gēmā) Level 2: A form accessed from the Toukenden Gaim (刀剣伝ガイム, Tōken-den Gaimu, Swords Legend Gaim) Gashat that arms him with Kamen Rider Gaim's Daidaimaru. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Rider Stage.
• Double Fighter Gamer Level 39 (ダブルファイターゲーマーレベル39, Daburu Faitā Gēmā Reberu Sāti Nain): A form accessed from the sequel-themed Knock Out Fighter 2 (ノックアウトファイター2, Nokku Auto Faitā Tsū) Gashat alongside Parad that grants increased offensive capabilities. Their finisher in this form is the Critical Knuckle (クリティカルナックル, Kuritikaru Nakkuru). These forms appear exclusively in the Kamen Rider Para-DX Hyper Battle DVD special.
• Creator Gamer (クリエイターゲーマー, Kurieitā Gēmā): A form accessed from the virtual reality-themed Mighty Creator VRX (マイティクリエイターVRX, Maiti Kurieitā Bui Āru Ekkusu) Gashat that grants the ability to create weapons, obstacles, and traps. This form appears exclusively in the film Kamen Rider Ex-Aid the Movie: True Ending.
• Novel Gamer Level X (ノベルゲーマー レベルX, Noberu Gēmā Reberu Ekkusu): A form accessed from the visual novel-themed Mighty Novel X Gashat that grants invincibility and reality alteration. His finisher in this form is the Critical Destiny (クリティカルデスティニー, Noberu Kuritikaru Desutinī). This form appears exclusively in the sequel novel Kamen Rider Ex-Aid: Mighty Novel X.

During the events of the film Kamen Rider × Super Sentai: Ultra Super Hero Taisen, Emu temporarily assumes the form of the red-colored Akarider (アカライダー, Akaraidā), a hybrid of Akarenger and the Double Riders. In this form, he can command the Variblune aircraft.

Emu Hojo is portrayed by Hiroki Iijima (飯島 寛騎, Iijima Hiroki). As a child, Emu is portrayed by Rai Takahashi (髙橋 來, Takahashi Rai).

Hiiro Kagami

Hiiro Kagami (鏡 飛彩, Kagami Hiiro) is a genius surgeon who recently returned from America, is described as a tsundere, and displays a liking for sweets due to his late girlfriend, Saki Momose. A prodigy in the medical field, Hiiro is initially passive-aggressive towards Emu Hojo due to their differing beliefs. However, the former slowly grows to respect the intern over time, even adopting some of his beliefs. Despite appearing callous, Hiiro does care for others.

During the first Zero Day incident, Momose was infected with the Bugster Virus, but she had kept it secret from Hiiro due to his aloof attitude until he eventually learned what had happened when Graphite manifested from her. When Taiga Hanaya fails to defeat the Bugster, Momose dies and Hiiro develops a grudge against Hanaya and Graphite despite harboring guilty feelings for himself. With Emu's help, Hiiro eventually accepts that he had partially contributed to Momose's death and reconciles with him. Amidst the Kamen Rider Chronicle crisis, Hiiro discovers Momose is among the Bugster Virus-infected victims whose life forces are stored in the Proto-Gashats and is blackmailed into joining Masamune Dan, who threatens to delete her data unless Hiiro serves him. After remembering Momose's last words however, Hiiro rejoins CR to defeat Masamune, guide new interns, and make peace with his past.

During the events of the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending, Hiiro reconciles with Hanaya before joining forces with him to defeat Lovrica, who had brainwashed a temporarily resurrected Momose. Before she dies once more, Hiiro comes to terms with her first death.

Utilizing the Gamer Driver in conjunction with the role-playing game-themed Taddle Quest (タドルクエスト, Tadoru Kuesuto) Gashat, Hiiro can transform into Kamen Rider Brave (仮面ライダーブレイブ, Kamen Raidā Bureibu) Quest Gamer Level 1 (クエストゲーマー, Kuesuto Gēmā) Level 1. In this form, he wields the Reversal Shield (リバーサルシールド, Ribāsaru Shīrudo), can perform flaming dash attacks, and transform further into Quest Gamer Level 2. In both forms, he wields the Gashacon Sword (ガシャコンソード, Gashakon Sōdo), which can switch between Fire Mode (炎モード, Honō Mōdo) and Ice Mode (氷モード, Kōri Mōdo). Additionally, activating Taddle Quest generates a Game Area and Energy Items randomly hidden inside treasure chest-like containers. Moreover, he can combine Taddle Quest with additional Gashats to achieve stronger forms, which are as follows:

• Beat Quest Gamer Level 3 (ビートクエストゲーマーレベル3, Bīto Kuesuto Gēmā Reberu Surī): A form accessed from Taddle Quest and the rhythm game-themed DoReMiFa Beat (ドレミファビート, Doremifa Bīto) Gashat that equips him with the right arm-mounted DoReMiFa Turntable (ドレミファターンテーブル, Doremifa Tāntēburu) phonograph and the left shoulder-mounted Watts Up Sounder (ワッツアップサウンダー, Wattsu Appu Saundā) speaker. To compensate for his lack of experience in rhythm games, he incorporates CPR techniques into his attacks.
• Hunter Quest Gamer Level 5 (Dragon Blade) (ハンタークエストゲーマーレベル5 (ドラゴンブレード), Hantā Kuesuto Gēmā Reberu Faibu (Doragon Burēdo)): A form accessed from the Taddle Quest and Drago Knight Hunter Z Gashats alongside one to three other Gamer Riders that equips him with the right arm-mounted Drago Knight Blade (ドラゴナイトブレード, Dorago Naito Burēdo) electromagnetic sword.
  • Hunter Quest Gamer Level 5 (Full Dragon) (ハンタークエストゲーマーレベル5 (フルドラゴン), Hantā Kuesuto Gēmā) Level 5 (Full Dragon): A stronger variant form that equips him with the Horn Drago Helm, the Whip Drago Tail, and the Drago Knight Gun along with the Drago Knight Blade.
• Famista Quest Gamer (ファミスタクエストゲーマー, Famisuta Kuesuto Gēmā): A form accessed from Taddle Quest and the Family Stadium-themed Famista (ファミスタ, Famisuta) Gashat that equips him with the Braver Grab (ブレイバーグラブ, Bureibā Gurabu) baseball glove and the left shoulder-mounted Play Ball Shooter (プレイボールシューター, Purei Bōru Shūtā) pitching machine. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Gamer Stage.
• Safari Quest Gamer Level 4 (サファリクエストゲーマーレベル4, Safari Kuesuto Gēmā Reberu Fō): A form accessed from Taddle Quest and the hunting simulation game-themed Night of Safari (ナイトオブサファリ, Naito Obu Safari) Gashat that equips him with the right arm-mounted Safari Night Blade (サファリナイトブレード, Safari Naito Burēdo) sword and the left arm-mounted Safari Night Gun (サファリナイトガン, Safari Naito Gan) cannon. This form appears exclusively in the web-exclusive special Kamen Rider Brave: Survive! The Revived Beast Rider Squad.
• Galaxian Quest Gamer (ギャラクシアンクエストゲーマー, Gyarakushian Kuesuto Gēmā): A form accessed from Taddle Quest and the Galaxian (ギャラクシアン, Gyarakushian) Gashat that equips him with the chest-mounted Beam Galashooter (ビームギャラクシューター, Bīmu Gyarakushūtā) laser cannon. This form appears exclusively in the film Kamen Rider × Super Sentai: Ultra Super Hero Taisen.

Additionally, Hiiro can achieve the following forms by utilizing unique Gashats in place of Taddle Quest:

• Fantasy Gamer Level 50 (ファンタジーゲーマーレベル50, Fantajī Gēmā Reberu Fifuti): A form accessed from the tactical role-playing game-themed Taddle Fantasy (タドルファンタジー, Tadoru Fantajī) side of the double-sized Gashat Gear Dual β (ガシャットギアデュアルβ, Gashatto Gia Dyuaru Bēta) that grants telekinesis, levitation capabilities, portal generation, creation of magical sword projections, and the ability to nullify Energy Items' effects. His finisher in this form is the Critical Slash (クリティカルスラッシュ, Kuritikaru Surasshu).
• Legacy Gamer Level 100 (レガシーゲーマーレベル100, Regashī Gēmā Reberu Handoreddo): A form accessed from Another Hiiro's Taddle Legacy Gashat that grants health recovery capabilities, which can be used on himself or allies, and the ability to create energy arrows. His finishers in this form are enhanced versions of his original Critical Strike and Finish finishers, which increase in power if one of his allies is defeated in battle.

Hiiro Kagami is portrayed by Toshiki Seto (瀬戸 利樹, Seto Toshiki).

Poppy Pipopapo

Poppy Pipopapo (ポッピーピポパポ, Poppī Pipopapo) is a Bugster based on a video game character from the fictional rhythm game DoReMiFa Beat who is able to assume a human guise called Asuna Karino (仮野 明日那, Karino Asuna),^{[lower-alpha 1]} works as a nurse for CR, and as a navigator for the Gamer Riders. She was born from Kuroto Dan's mother, Sakurako Dan (檀 櫻子, Dan Sakurako), who had helped him during his youth before he infected her with the Bugster Virus in an attempt to save her from an unknown regular illness.

Following Kuroto's first death, Pipopapo falls under Lovrica's sway and helps him and Parad complete the Kamen Rider Chronicle Gashat before serving as the Kamen Rider Chronicle crisis' referee and navigator. After Masamune kills Lovrica, Emu Hojo saves her from the latter's brainwashing. Wishing to redeem herself, Pipopapo revives Kuroto as a Bugster to help the Gamer Riders defeat Masamune. While she later sacrifices herself to do so, Kuroto uses a fragment of her data to restore her.

As a Bugster, Pipopapo is able to turn cutlery into energy weapons, utilize Energy Items' powers, and enter a level selected by the Kamen Riders. While working for Lovrica, she receives a Bugster Buckle II (バグスターバックルII, Bagusutā Bakkuru Tsuvai, Bugster Buckle Zwei) belt and Gashacon Bugvisor II (ガシャコンバグヴァイザーII, Gashakon Baguvaizā Tsuvai, Gashacon Bugvisor Zwei), both of which she can combine to form the Buggle Driver II (バグルドライバーII, Baguru Doraibā Tsuvai, Buggle Driver Zwei) and use in conjunction with the dating simulation-themed Toki Meki Crisis (ときめきクライシス, Toki Meki Kuraishisu, Heartthrob Crisis) Gashat to transform into Kamen Rider Poppy (仮面ライダーポッピー, Kamen Raidā Poppī) Toki Meki Crisis Gamer Level X (ときめきクライシスゲーマーレベルX, Toki Meki Kuraishisu Gēmā Reberu Ekkusu). While transformed, she can wield the Gashacon Bugvisor II, possesses immunity against conventional attacks, and perform the Critical Crews-Aid (クリティカルクルセイド, Kuritikaru Kuruseido) finisher.

Poppy Pipopapo / Asuna Karino is portrayed by Ruka Matsuda (松田 るか, Matsuda Ruka).

Taiga Hanaya

Taiga Hanaya (花家 大我, Hanaya Taiga) is an unlicensed radiologist who is known as the "dark doctor" (闇のドクター, Yami no Dokutā). Five years prior to the series, while working for the Seito University Hospital's radiology department, he had been chosen by CR to become a Kamen Rider after detecting the Bugster Virus in one of his patients. He initially refused due to his many responsibilities until his partner, Jiro Maki (牧 治郎, Maki Jirō), made an attempt to take his place and suffered grievous injuries due in part to not being immunized against the Bugster Virus. Taiga begrudgingly accepted CR's offer, but failed to defeat the Bugster, Graphite, and save his patient, Saki Momose. After leaving CR and having his medical license revoked, he opened an illegal medical practice in an abandoned hospital and trained to protect himself from the side effects of becoming a Gamer Rider.

In the present, he receives Rider equipment from Kuroto Dan with the intention of taking the other Gamer Riders' equipment and the burden of being a Rider for himself. While Taiga gradually comes to accept his fellow Riders, he also grapples with his guilt and shame for failing to save Saki. Because of this, he deliberately attempts to antagonize Saki's boyfriend, Hiiro Kagami, believing he deserves the latter's scorn, though the two eventually reconcile. Prior to and during the Kamen Rider Chronicle crisis, Hanaya reluctantly takes on Nico Saiba as an apprentice and works with the Gamer Riders to stop its mastermind, Masamune Dan. Following this, Taiga regains his medical license and opens a hospital to treat the Bugster Virus.

Utilizing a Gamer Driver in conjunction with the shooter game-themed Bang Bang Shooting (バンバンシューティング, Ban Ban Shūtingu) Gashat, Hanaya can transform into Kamen Rider Snipe (仮面ライダースナイプ, Kamen Raidā Sunaipu) Shooting Gamer (シューティングゲーマー, Shūtingu Gēmā) Level 1. In this form, he can turn himself into an energy bullet and transform further into Shooting Gamer Level 2. In both forms, he wields the Gashacon Magnum (ガシャコンマグナム, Gashakon Magunamu), which can switch between Handgun Mode (ハンドガンモード, Handogan Mōdo) and Rifle Mode (ライフルモード, Raifuru Mōdo). Additionally, activating Bang Bang Shooting generates a Game Area and Energy Items randomly hidden inside drum-like containers. Moreover, he can combine Bang Bang Shooting with additional Gashats to achieve stronger forms, which are as follows:

• Combat Shooting Gamer Level 3 (コンバットシューティングゲーマーレベル3, Konbatto Shūtingu Gēmā Reberu Surī): A form accessed from Bang Bang Shooting and the shoot 'em up-themed Jet Combat (ジェットコンバット, Jetto Konbatto) Gashat that equips him with the Air Force Winger (エアフォースウィンガー, Ea Fōsu Wingā) jetpack and the twin Gatling Combat (ガトリングコンバット, Gatoringu Konbatto) rotary guns.
• Hunter Shooting Gamer Level 5 (Dragon Gun) (ハンターシューティングゲーマーレベル5 (ドラゴンガン), Hantā Shūtingu Gēmā Reberu Faibu (Doragon Gan)): A form accessed from the Bang Bang Shooting and Drago Knight Hunter Z Gashats along with one to three other Gamer Riders that equips him with the left arm-mounted Drago Knight Gun (ドラゴナイトガン, Dorago Naito Gan) electromagnetic cannon.
  • Hunter Shooting Gamer Level 5 (Full Dragon) (ハンターシューティングゲーマーレベル5 (フルドラゴン), Hantā Shūtingu Gēmā Reberu Faibu (Furu Doragon)): A stronger variant form that equips him with the Horn Drago Helm, the Whip Drago Tail, and the Drago Knight Blade along with the Drago Knight Gun.
• Xevious Shooting Gamer (ゼビウスシューティングゲーマー, Zebiusu Shūtingu Gēmā): A form accessed from Bang Bang Shooting and the Xevious (ゼビウス, Zebiusu) Gashat that equips him with the Solval Wing (ソルバルウィング, Sorubaru Wingu) jetpack and the twin Gatling Zapper (ガトリングザッパー, Gatoringu Zappā) rotary guns. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Gamer Stage.

Additionally, Hanaya can achieve the following forms by utilizing unique Gashats in place of Bang Bang Shooting:

• Simulation Gamer Level 50 (シミュレーションゲーマーレベル50, Shimyurēshon Gēmā Reberu Fifuti): A form accessed from the naval simulation game-themed Bang Bang Simulations (バンバンシミュレーションズ, Ban Ban Shimyurēshonzu) side of the Gashat Gear Dual β that grants increased shooting accuracy as well as equip him with the twin arm-mounted Overblast Cannons (オーバーブラストキャノン, Ōbāburasuto Kyano) and the twin shoulder-mounted Scramble Gun Unit (スクランブルガンユニット, Sukuranburu Gan Yunitto) turrets. His finisher in this form is the Critical Fire (クリティカルファイヤー, Kuritikaru Faiyā).
• Kamen Rider Proto Snipe (仮面ライダープロトスナイプ, Kamen Raidā Puroto Sunaipu) Shooting Gamer Level 1 (Proto) (シューティングゲーマーレベル1 [プロト], Shūtingu Gēmā Reberu Wan [Puroto]): Hanaya's original Rider form accessed from the beta test-themed Proto Bang Bang Shooting (プロトバンバンシューティング, Puroto Ban Ban Shūtingu) Gashat, which he discontinued use of after its negative side effects nearly killed him.

Amidst the Kamen Rider Chronicle crisis, Hanaya acquires two Kamen Rider Chronicle Gashats and uses them in conjunction with the Gamer Driver to transform into Kamen Rider Cronus. While his incomplete Bugster Virus antibodies prevent him from accessing Cronus' full power, Hanaya instead gains access to his teammates' Gashacon Weapons. In the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending, he acquires Poppy Pipopapo's Buggle Driver II and uses it with the Kamen Rider Chronicle Master Gashat in order to properly access Cronus' full power.

Taiga Hanaya is portrayed by Ukyo Matsumoto (松本 享恭, Matsumoto Ukyō).

Kuroto Dan

Kuroto Dan (檀 黎斗, Dan Kuroto) is the cold-blooded, manipulative, and narcissistic CEO and founder of the Genm Corp. (幻夢コーポレーション, Genmu Kōporēshon, Fantasy Dream Corporation) game company and son of previous CEO Masamune who believes his intelligence is something to be feared. Despite himself, Kuroto puts on a calm and polite front in public and select individuals he requires for his plans. Having created games for Masamune as a teenager and believing only he was capable of making great games, Kuroto develops a grudge against a young Emu Hojo, who had submitted game ideas that the former perceived as better than his. After becoming one of the first people to discover the Bugster Virus 16 years prior to the series, he infects Emu with it and studies him over the course of a decade before extracting the virus and using it to create the Bugsters. However, Kuroto's mother Sakurako also became infected with the Bugster Virus while helping him and died, leading to him losing his sanity, causing Zero Day via Proto Gashats (プロトガシャット, Puroto Gashatto), and framing Masamune for it five years prior to the series.

Following the epidemic, Kuroto contributes to the Ministry of Health's CR division and Rider systems to combat the Bugsters using his polite facade while also helping the monsters battle the Riders as Kamen Rider Genm (仮面ライダーゲンム, Kamen Raidā Genmu)^{[lower-alpha 2]} in order to collect the Gashats' data and create one for the "Ultimate Game" Kamen Rider Chronicle (仮面ライダークロニクル, Kamen Raidā Kuronikuru), a global augmented reality, massively multiplayer online game death battle with him as the "Game Master", all in an attempt to resurrect Sakurako. Upon manipulating the Gamer Riders into "clearing" 10 Gashats' data, Kuroto allows Emu to give him a "game over" so the former can use the death data to create the Dangerous Zombie Gashat before killing Kiriya Kujo for nearly exposing his identity. Despite this, Kuroto's machinations are revealed and he becomes a fugitive, stealing the Riders' Gashats along the way until Emu defeats Kuroto and Parad kills him.

When the Bugsters take over Gemn Corp. and attempt to use Kamen Rider Chronicle to replace humanity with more of their kind, Poppy Pipopapo discovers she was born from Sakurako, who had hidden a Gamer Driver and the Proto Mighty Action X Origin Gashat as a failsafe, and uses the equipment to revive Kuroto as a Bugster with 99 lives. With his new lease on life, he christens himself "New Kuroto Dan" (新檀 黎斗, Shin Dan Kuroto) and joins forces with the Gamer Riders to exact revenge on Parad, revive Kiriya as a Bugster as well, and stop the Bugsters, with Pipopapo using Sakurako's memories to keep him in line. In the process, Kuroto discovers Masamune had manipulated him from the beginning and helps CR develop the Hyper Muteki Gashat so Emu can defeat Masamune and the Doctor Mighty XX Gashat to cure Bugster Virus victims and weaken Kamen Rider Chronicle's final boss, Gamedeus, losing a majority of his lives in the process. While Kiriya has Kuroto arrested, the latter changes his name to "Kuroto Dan Shin" (檀 黎斗 神, Dan Kuroto Shin)^{[lower-alpha 3]} to reflect his god complex and continues to advise CR until Masamune and Gamedeus are defeated.

During the events of the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending, Kuroto uses his last life to initiate a universal apocalypse through a multiplayer survival horror game called Zombie Chronicle (ゾンビクロニクル, Zonbi Kuronikuru). While he is ultimately defeated by Kujo, Kuroto regains his sanity before disappearing.

During the events of the web-exclusive series, Kamen Sentai Gorider, which takes place before Kuroto's revival as a Bugster, a backup of him disguises himself as Kazuma Kenzaki to lure deceased Kamen Riders Kiriya, Kaoru Kino, Kaito Kumon, and Yoko Minato into a Game World and use their despair to resurrect himself. However, Emu, the fallen Riders, and the real Kazuma foil him via the Goriders's power.

During the events of the two-part web-exclusive special Kamen Rider Genms: The Presidents, which takes place after the series, an artificial intelligence called the Ark digitally revives Kuroto, who infects Gai Amatsu with a unique strain of the Bugster Virus in order to materialize himself in the physical world and regain control of Gemn Corp. so he can use it for malicious means. While a revived Masamune interrupts Kuroto's plans, Amatsu convinces the Dans to reconcile before the father-and-son pair return to the digital world. Despite this, Kuroto vows to return.

During the events of the web-exclusive special Kamen Rider Genms: Smart Brain and the 1000% Crisis, Kuroto is revived as a Humagear and manipulates Amatsu into transferring control of the latter's company, Thouser-Intellion, to him under the Ark's orders.

As of the web-exclusive series Kamen Rider Outsiders, he created a new company, Genm Musou Corp. (幻夢無双コーポレーション, Genmu Musō Kōporēshon).

Utilizing a Gamer Driver and the beta test-themed Proto Mighty Action X (プロトマイティアクションX, Puroto Maiti Akushon Ekkusu) Gashat, Kuroto can transform into Kamen Rider Gemn Action Gamer Level 1. In this form, he gains increased agility and can transform further into Action Gamer Level 2. In both forms, he possesses greater power than Emu as Ex-Aid due to Kuroto's Proto Gashat having unlimited powers, though prolonged use will harm him, and wields the Gashacon Bugvisor (ガシャコンバグヴァイザー, Gashakon Baguvaizā), which can switch between Pad Mode (パッドモード, Paddo Mōdo), Beam Gun Mode (ビームガンモード, Bīmu Gan Mōdo), and Chainsaw Mode (チェーンソーモード, Chēnsō Mōdo) as well as absorb Bugsters' data and trap them within it. Additionally, activating Proto Mighty Action X generates a Game Area and several Energy Items randomly hidden inside chocolate block-like containers. Moreover, he can combine Proto Mighty Action X with additional Gashats to achieve stronger forms, which are as follows:

• Sports Action Gamer Level 3 (スポーツアクションゲーマーレベル3, Supōtsu Akushon Gēmā Reberu Surī): A form accessed from Proto Mighty Action X and the sports game-themed Shakariki Sports (シャカリキスポーツ, Shakariki Supōtsu, Enthusiastic Sports) Gashat that arms him with the twin Trick Flywheel (トリックフライホイール, Torikku Furaihoīru) throwing discs. The Shakariki Sports Gashat first appears in the penultimate episode of Kamen Rider Ghost.

After creating the survival horror-themed Dangerous Zombie (デンジャラスゾンビ, Denjarasu Zonbi) Gashat, Kuroto combines the Gashacon Bugvisor with the Bugster Buckle (バグスターバックル, Bagusutā Bakkuru) belt to form the Buggle Driver (バグルドライバー, Baguru Doraibā) and use it conjunction with the Gashat to transform into Kamen Rider Gemn Zombie Gamer Level X (ゾンビゲーマーレベルX, Zonbi Gēmā Reberu Ten/Ekkusu). While transformed, he can command zombie-themed Bugster Viruses created upon Dangerous Zombie's activation, regenerate from injuries, circumvent death, and wield the Gashacon Bugvisor, though he can also wield Gashacon Weapons so long as he has the corresponding Gashats. His finishers in this form are the Critical End (クリティカルエンド, Kuritikaru Endo) and the Critical Dead (クリティカルデッド, Kuritikaru Deddo). Using this form, he allows the other Riders to defeat him in order to absorb more death data and evolve his Rider form into Genm X (ゲンムX, Genmu Ekksu) until Emu uses Maximum Mighty X to remove most of his power.

After being revived as a Bugster, Kuroto uses a Gamer Driver in conjunction with the alpha build-themed Proto Mighty Action X Origin (プロトマイティアクションXオリジン, Puroto Maiti Akushon Ekkusu Orijin) to transform into Kamen Rider Gemn Action Gamer Level 0 (Proto Origin) (レベル0 [プロトオリジン], Reberu Zero [Puroto Orijin]). While transformed, he can utilize his extra lives, nullify the Bugster Virus' effects, weaken Gamer Riders, and wields the Gashacon Bugvisor II and Gashacon Breaker. Moreover, he can combine Proto Mighty Action X Origin with additional Gashats to achieve stronger forms, which are as follows:

• Zombie Action Gamer Level X-0 (ゾンビアクションゲーマーレベルX-0, Zonbi Akushon Gēmā Reberu Ekkusu Zero): A form accessed from the Proto Mighty Action X Origin and Dangerous Zombie Gashats that grants increased power compared to his original Zombie Gamer form due to the former Gashat negating the latter's negative side effects.
• Proto Sports Action Gamer Level 0 (プロトスポーツアクションゲーマーレベル0, Puroto Supōtsu Akushon Gēmā Reberu Zero): A form accessed from the Proto Mighty Action X Origin and Proto Shakariki Sports Gashats that arms him with the Trick Flywheels. This form appears exclusively in the Kamen Rider Lazer Hyper Battle DVD special.

Additionally, Kuroto can achieve the following forms by utilizing unique Gashats in place of his regular Gashats:

• Wizard Gamer (ウィザードゲーマー, Wizādo Gēmā) Level 1 and 2: A chibi-like form and its subsequent sleeker upgrade, both of which are accessed from the Magic the Wizard (マジックザウィザード, Majikku Za Wizādo) Gashat that arms him with Kamen Rider Wizard's WizarSwordGun. These forms appear exclusively in the web-exclusive special Kamen Rider Genm: Legend Rider Stage.
• God Maximum Gamer Level 1000000000 (ゴッドマキシマムゲーマーレベルビリオン, Goddo Makishimamu Gēmā Reberu Birion): A mecha-like form accessed from the double-sized mecha simulation game-themed God Maximum Mighty X (ゴッドマキシマムマイティX, Goddo Makishimamu Maiti Ekkusu) Gashat that automatically transforms him into his Action Gamer Level 0 form and grants the use of the God Maximum Gama (ゴッドマキシマムゲーマ, Goddo Makishimamu Gēma) armored suit capable of flying and extending its limbs, which Kuroto can separate from and leave on autopilot while maintaining his Level 1000000000 power, celestial body manipulation, immunity to Kamen Rider Cronus' chronokinetic abilities, the ability to summon a horde of his Zombie Gamer form capable of turning people into zombie Bugster Viruses, and acidic breath. His finisher in this form is the Critical Blessing (クリティカルブレッシング, Kuritikaru Buresshingu). This form appears exclusively in the V-Cinema Kamen Rider Ex-Aid Trilogy: Another Ending.
• Musou Gamer (無双ゲーマー, Musō Gēmā): A form accessed from the Genm Musou (幻夢無双, Genmu Musō) Gashat and absorbing the Ark's data on malice. His finisher in this form is the Critical Finale (クリティカルフィナーレ, Kuritikaru Fināre). This form appears exclusively in the web-exclusive special Kamen Rider Genms: Smart Brain and the 1000% Crisis.

Kuroto Dan is portrayed by Tetsuya Iwanaga (岩永 徹也, Iwanaga Tetsuya). As a teenager, Kuroto is portrayed by Mitsumasa Sato (佐藤 光将, Satō Mitsumasa). Iwanaga's portrayal of Kuroto throughout the series, especially after his character's descent to insanity and eventual revival as a comical maniac, proved highly popular among audiences.

Parad

Parad (パラド, Parado) is a leading Bugster and the first to manifest after Kuroto Dan infected Emu Hojo 16 years prior to the series. Unlike the other Bugsters, Parad lacks a monstrous form and is the physical manifestation of Emu's childhood desire for a playmate. As such, the former enjoys fighting his host, though he is also protective of his kind and hateful of humanity's pride. While he was a part of Emu's body, Parad dominated his "Genius Gamer M" persona and helped him enjoy popularity as a gamer.

Five years prior to the series however, Kuroto tasked the Next Genome Institute with extracting the Bugster Virus in Emu's body for his plans. As a result, Parad manifested to protect Emu, with the resulting separation causing the latter to pursue his dream of becoming a doctor while maintaining aspects of his gamer personality due to traces of Parad still being in him.

In the present, Parad joins forces with Kuroto to help him complete the Kamen Rider Chronicle project while occasionally helping Emu. After using Kuroto to become Kamen Rider Para-DX (仮面ライダーパラドクス, Kamen Raidā Paradokusu), Parad eventually abandons and kills him to take over Kamen Rider Chronicle to help the Bugsters eliminate humanity. During this time, Parad re-possesses Emu to obtain a DNA sample to upgrade his Rider powers and force Emu to fight the other Riders until a revived Kuroto defeats the Bugster while seeking revenge. When Masamune Dan reveals he had manipulated everyone involved in Kamen Rider Chronicle and kills one of his fellow Bugsters, Parad becomes fearful of suffering the same fate and confronts Emu, who defeats and reabsorbs him. Acknowledging his fear of death and feeling remorse over his actions, Parad works with Emu to stop Masamune. While he sacrifices himself in order to do so, a fragment of him remained in Emu's body, which he later uses to revive Parad.

In addition to the standard Bugster abilities, Parad possesses the ability to teleport and project force fields. Being Emu's Bugster, Parad can also assume control of the right half of the former's Double Action Gamer Level XX form.

Utilizing the double-sized Gashat Gear Dual (ガシャットギアデュアル, Gashatto Gia Dyuaru), which generates a Game Area with several exposed Energy Items, Parad can transform into Kamen Rider Para-DX Level 50 (レベル50, Reberu Fifuti). Due to the Gashat Gear Dual's nature, he can assume one of two forms, which are as follows:

• Puzzle Gamer (パズルゲーマー, Pazuru Gēmā): Parad's blue-colored primary form accessed from the puzzle game-themed Perfect Puzzle (パーフェクトパズル, Pāfekuto Pazuru) side of the Gashat Gear Dual that grants the ability to manipulate numerous Energy Items, combine their powers for himself, and generate energy shields. His finisher in this form is the Critical Combo (クリティカルコンボ, Kuritikaru Konbo).
• Fighter Gamer (ファイターゲーマー, Faitā Gēmā): Parad's red-colored secondary form accessed from the fighting game-themed Knock Out Fighter (ノックアウトファイター, Nokku Auto Faitā) side of the Gashat Gear Dual that grants superhuman strength, pyrokinesis, and equips him with the Materialize Smasher (マテリアライズスマッシャー, Materiaraizu Sumasshā) gauntlets. His finisher in this form is the Critical Smash (クリティカルスマッシュ, Kuritikaru Sumasshu).

After claiming Kuroto's Gamer Driver, Parad uses the Gashat Gear Dual in conjunction with it to transform into the hybrid game-themed Kamen Rider Para-DX Perfect Knock Out Gamer Level 99 (パーフェクトノックアウトゲーマーレベル99, Pāfekuto Nokku Auto Gēmā Reberu Nainti Nain). While transformed, he can utilize and combine both of his Level 50 forms' powers. He also wields the Gashacon Parabragun (ガシャコンパラブレイガン, Gashakon Parabureigan), which can switch between Axe Mode and Gun Mode as well as utilize either two normal-sized Gashats or one double-sized Gashat to activate its Critical Finish. With the Mighty Brothers XX Gashat, Parad can temporarily split into his Level 50 forms. His finishers in this form are enhanced versions of his original Critical Combo and Smash finishers, as well as the Critical Bomber (クリティカルボンバー, Kuritikaru Bonbā).

During the events of the Kamen Rider Para-DX Hyper Battle DVD special, Parad and Emu utilize the Knock Out Fighter 2 Gashat in conjunction with their Gamer Drivers to transform into Kamen Riders Para-DX and Ex-Aid Double Fighter Gamer Level 39.

Parad is portrayed by Shouma Kai (甲斐 翔真, Kai Shōma).

Kiriya Kujo

Kiriya Kujo (九条 貴利矢, Kujō Kiriya) is a cunning medical examiner who investigates the Bugsters and their origins out of curiosity and after losing his friend Jungo Aihara (藍原 淳吾, Aihara Jungo) during Zero Day. In pursuit of his goal, the former discovers Kuroto Dan is Kamen Rider Gemn and reveals his identity to the other Riders, but is eventually killed for it. Prior to this, Kiriya left research for a cure to the Bugster Virus with his colleague, Yoshitaka, who later gives it to Kiriya's allies.

During the events of the web-exclusive miniseries Kamen Sentai Gorider, Kuroto arranges the resurrection of Kiriya, among other deceased Riders, to lure Emu Hojo to the Game World and kill him. However, Kazuma Kenzaki arrives to help Emu and the revived Riders stop Kuroto. During the fight, Kiriya transforms into the yellow-colored Kirider (キライダー, Kiraidā) before joining the fallen Riders in sacrificing themselves to defeat Kuroto and ensure Emu and Kazuma's escape.

Amidst the Kamen Rider Chronicle crisis, Masamune Dan revives Kujo as a Bugster to serve him. However, the latter secretly works against him before eventually rejoining the Gamer Riders to stop Masamune. Following this, Kujo is nominated to become an official member of CR and collaborates with Tsukuru Koboshi to develop Bugster Virus vaccines.

During the events of the V-Cinema Kamen Rider Ex-Aid Trilogy: Another Ending, a dying Masamune tasks Kujo with foiling Kuroto's plot to destroy the universe and nearly dies again, though Hiiro Kagami is able to revive Kujo and restore his humanity.

Prior to his revival in the series, Kiriya's death had become a popular hashtag in Japan's Twitter feed under the slogan, "Why did Kiriya have to Die So Soon?" (なんできりやすぐ死んでしまうん, Nande Kiriya sugu shinde shimaun), based on the advertising slogan of the animated film Grave of the Fireflies. Toei Company took note of this and quickly issued an apology.^[1]

Utilizing a Gamer Driver in conjunction with the racing game-themed Bakusou Bike (爆走バイク, Bakusō Baiku, Burnout Bike) Gashat, Kujo can transform into Kamen Rider Lazer (仮面ライダーレーザー, Kamen Raidā Rēzā) Bike Gamer (バイクゲーマー, Baiku Gēmā) Level 1. In this form, he wields the Front Armed Unit (フロントユニット, Furonto Āmudo Yunitto) knuckleduster and the Rear Armed Unit (リアアームドユニット, Ria Āmudo Yunitto) gun, can perform spin attacks, and transform further into his motorcycle-like Bike Gamer Level 2 form. Additionally, activating Bakusou Bike generates a Game Area and Energy Items randomly hidden inside trophy stand-like containers. While he is capable of moving in his Level 2 form and switching back to his Level 1 form on his own, he requires a partner to help him activate his finishers. Moreover, he can combine Bakusou Bike with additional Gashats to achieve stronger forms, which are as follows:

• Chambara Bike Gamer Level 3 (チャンバラバイクゲーマーレベル3, Chanbara Baiku Gēmā Reberu Surī): A humanoid form accessed from Bakusou Bike and the hack and slash-themed Giri Giri Chambara (ギリギリチャンバラ, Giri Giri Chanbara, Slash Slash Sword Fight) Gashat that arms him with the Gashacon Sparrow (ガシャコンスパロー, Gashakon Suparō), which can switch between Bow Mode (弓モード, Yumi Mōdo) and Sickle Mode (鎌モード, Kama Mōdo).
• Hunter Bike Gamer Level 5 (Dragon Claw) (ハンターバイクゲーマーレベル5 [ドラゴンクロー], Hantā Baiku Gēmā Reberu Faibu [Doragon Kurō]): A humanoid form accessed from the Bakusou Bike and Drago Knight Hunter Z Gashats alongside one to three other Gamer Riders that equips him with the Drago Knight Blade and Gun.

After being revived by Masamune, Kujo utilizes the Gamer Driver and Bakusou Bike Gashat to transform into the humanoid Kamen Rider Lazer Turbo (仮面ライダーレーザーターボ, Kamen Raidā Rēzā Tābo) Bike Gamer Level 0 (レベル0, Reberu Zero). In this form, he gains the ability to nullify the Bugster Virus and wield the Gashacon Sparrow so long as he is in possession of Giri Giri Chambara. Additionally, Kujo can combine Bakusou Bike with beta test-themed Proto-Gashats to achieve the following forms:

• Proto Sports Bike Gamer (プロトスポーツバイクゲーマー, Puroto Supōtsu Baiku Gēmā) Level 0: A form accessed from Bakusou Bike and Proto Shakariki Sports (プロトシャカリキスポーツ, Puroto Shakariki Supōtsu, Proto Enthusiastic Sports) that arms him with the Trick Flywheels.
• Proto Combat Bike Gamer (プロトコンバットバイクゲーマー, Puroto Konbatto Baiku Gēmā) Level 0: A form accessed from Bakusou Bike and Proto Jet Combat (プロトジェットコンバット, Puroto Jetto Konbatto) that equips him with the Air Force Winger and the Gatling Combats.

During the events of the V-Cinema Kamen Rider Ex-Aid Trilogy: Another Ending, Kujo utilizes the Buggle Driver II and Giri Giri Chambara Gashat to transform into Kamen Rider Lazer X (仮面ライダーレーザーX, Kamen Raidā Rēzā Ekkusu). While transformed, he can perform the Critical Crews-Aid finisher.

Kiriya Kujo is portrayed by Hayato Onozuka (小野塚 勇人, Onozuka Hayato).

Masamune Dan

Masamune Dan (檀 正宗, Dan Masamune) is the original CEO of Genm Corp., the husband of Sakurako, and the father of Kuroto who orchestrated his son's schemes in an attempt to revive his wife after she had been infected with the Bugster Virus. Six years prior to the series, Masamune participated in Emu Hojo's life-saving surgery. Developing a god complex before secretly infecting himself with the Bugster Virus, allowing Kuroto to frame him for Zero Day, and willingly going to prison to incubate his virus in peace.

After being cleared of all charges and Kuroto and the Bugsters complete Kamen Rider Chronicle in the present, Masamune reclaims his position as Genm Corp.'s CEO and commercially releases the game so he can mass-produce its Gashats, release them worldwide, and turn its players into data. To further his plans, he also reprograms Kamen Rider Chronicle's final boss, Gamedeus, to obey him. When CR develop the means to defeat Gamedeus and end Kamen Rider Chronicle, Masamune absorbs the Bugster, transforms into Gamedeus Cronus (ゲムデウスクロノス, Gemudeusu Kuronosu), and causes a citywide epidemic, but Poppy Pipopapo and Parad sacrifice themselves to extract Gamedeus from Masamune and allow the Gamer Riders to defeat them. Despite this, Masamune commits suicide by subjecting himself to the Kamen Rider Chronicle Master Gashat's virus, taking it with him to prevent the Riders from freeing the game's victims.

In the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending, Kuroto revives Masamune to force him to help the former develop Zombie Chronicle in order to destroy the universe and serve as a host for Black Parad. Masamune later frees himself and attempts to stop Kuroto, but is fatally wounded in battle against his son. Before he dies, Masamune tells Kiriya Kujo the truth of how the former and Kuroto were driven to madness before giving Kujo his Buggle Driver II.

During the events of the two-part web-exclusive special Kamen Rider Gemn: The Presidents, after an artificial intelligence called the Ark revives Kuroto, who infects ZAIA Enterprise CEO Gai Amatsu with the Bugster Virus, Masamune emerges from Amatsu as a Bugster and fights Kuroto to stop him from using Gemn Corp. for malicious intent. However, Amatsu convinces the Dans to reconcile and the pair return to the digital world in peace.

Utilizing the Buggle Driver II and the Kamen Rider Chronicle Master Gashat, Masamune can transform into Kamen Rider Cronus (仮面ライダークロノス, Kamen Raidā Kuronosu) Chronicle Gamer (クロニクルゲーマー, Kuronikuru Gēmā). While transformed, he possesses chronokinesis via his Pause (ポーズ, Pōzu) and Reset (リセット, Risetto) abilities and wields the Gashacon Bugvisor II. His finishers in this form are the Critical Crews-Aid on his own and the Critical Judgment (クリティカルジャッジメント, Kuritikaru Jajjimento) and the Critical Sacrifice (クリティカルサクリファイス, Kuritikaru Sakurifaisu) via the Bugvisor II's Beam Gun and Chainsaw Modes respectively. Additionally, his Master Gashat allows him to manipulate Bugsters' lives and control Ride-Player casualties.

As Gamedeus Cronus, he wields Gamedeus' DeuSlasher and Deus Rampart and can transform into the Bugster's Super Gamedeus (超ゲムデウス, Chō Gemudeusu) form, which possesses the extendable Deus Fafnir (デウスファーブニル, Deusu Fābuniru) arms and the sword-like Deuscalibur (デウスカリバー, Deusukaribā) leg.

Masamune Dan is portrayed by Hiroyuki Takami (貴水 博之, Takami Hiroyuki).

Seito University Hospital

The Seito University Hospital (聖都大学附属病院, Seito Daigaku Fuzoku Byōin) is a prestigious medical facility that contains the Cyberbrain Room (電脳救命センター, Den'nō Kyūmei Sentā), abbreviated as CR, which operates under the authority of the Ministry of Health (衛生省, Eisei-shō) to isolate and rescue Bugster Virus victims. CR was formed five years prior to the series during Zero Day (ゼロデイ, Zero Dei), before the Bugster infection was made public.

To combat the Bugsters, CR developed Gamer Driver (ゲーマドライバー, Gēma Doraibā) belts and Rider Gashat (ライダーガシャット, Raidā Gashatto) cartridges from technology provided by Gemn Corp. to allow doctors who have been immunized against the Bugster Virus to transform into Kamen Riders. While transformed, they start out in chibi-esque Level 1 (レベル1, Reberu Wan) forms before they can upgrade into their sleeker Level 2 (レベル2, Reberu Tsū) forms via the Level Up (レベルアップ, Reberu Appu) function, change locations via the Stage Select (ステージセレクト, Sutēji Serekuto) function, and perform Critical Strike (クリティカルストライク, Kuritikaru Sutoraiku) finishers via the Kimewaza Slot Holder (キメワザスロットホルダー, Kimewaza Surotto Horudā, Finisher Technique Slot Holder) device. They also all wield multiform Gashacon Weapons (ガシャコンウェポン, Gashakon Uepon, Special Weapon) unique to them, which allows them to perform Critical Finish (クリティカルフィニッシュ, Kuritikaru Finisshu) finishers.

Bugsters

The Bugsters (バグスター, Bagusutā), also known as Bugster Viruses (バグスターウイルス, Bagusutā Uirusu), are sentient, monstrous, microscopic computer viruses born from the Year 2000 problem that aim to destroy humanity and rule the world. After Kuroto Dan discovered them during the millennium turnover, his father Masamune infected himself with the original Bugster Virus before he manipulated Kuroto into doing the same to Emu Hojo in order to breed the Bugsters themselves.

Following Zero Day, the Bugsters are developed from humans infected with the Bugster Virus. Using their host's negative emotions, the monsters are able to take control of them and transform them into giant Bugster Union (バグスターユニオン, Bagusutā Yunion) monsters. Once a Rider extracts the Bugster from the host, the former will manifest in their complete form alongside a group of Bugster Virus foot soldiers while the host will revert to their human form and suffer from the effects of Game Disease (ゲーム病, Gēmu-byō). Unless their corresponding Bugster is destroyed or dealt with quickly, the host will turn into data and the former fully manifests with additional powers, such as the ability to assume human forms. Due to negative emotions fueling the Bugster Virus and Game Disease, stressors can potentially cause the host to spawn additional Bugster Virus foot soldiers or duplicates of the original Bugster monster. If a Bugster's physical body is destroyed without someone absorbing their essence, they will die permanently, though fully manifested Bugsters possess immortality and can be revived multiple times. Despite all of this, a person afflicted with the Bugster Virus or Game Disease can overcome their condition via positive emotions.

After Graphite attempts to cause a second Zero Day, the Bugsters evolve to the point where they can attain their monstrous forms without assuming Bugster Union forms, retain memories from past battles, "level up" along with the Gamer Riders, take over their host's body by killing their mind, and eventually, the ability to manifest without a host.

Being born from video games, the Bugsters behave similarly to artificial intelligences and follow their corresponding games' rules. As such, some take on an antagonistic role and fight their hosts while others behave like support characters and aid their hosts. Regardless of whether they are in opposition or cooperation with each other, they all follow the rules and treat each other fairly.

Saki Momose

Saki Momose (百瀬 小姫, Momose Saki) is a deceased medical student at Seito University and Hiiro Kagami's girlfriend. Five years prior to the series, Kuroto Dan secretly infected her with the Bugster Virus and provoked her into worsening her condition, which she kept secret from Hiiro so as not to distract him from his work and due to him treating her coldly. Taiga Hanaya attempted to save her, but due to being weakened from his use of a Proto Gashat, he was unable to save her nor stop the emerging Graphite. Before she died and turned into data stored in the Proto Drago Knight Hunter Z Gashat, she asked Hiiro to become the greatest doctor in the world.

In the present, Masamune Dan steals the Proto Gashats from the Ministry of Health and bribes Hiiro into helping him maintain Kamen Rider Chronicle by promising to restore Saki. After the former threatens to delete her data unless the latter willfully botches a surgery meant to save Taiga however, Hiiro chooses to maintain his integrity as a doctor and refuses, leading to Masamune seemingly deleting Saki's data.

During the events of the V-Cinema Kamen Rider Ex-Aid Trilogy: Another Ending, Kuroto temporarily resurrects Momose, but a similarly revived Lovrica subsequently brainwashes her. Hiiro and Hanaya succeed in defeating the Bugster and freeing her, only to learn of what Kuroto did. Despite this, Momose tells Hiiro she had forgiven him for how he treated her and gives him the strength to come to terms with her death before she dies once more.

Saki Momose is portrayed by Kana Nakagawa (中川 可菜, Nakagawa Kana).

Nico Saiba

Nico Saiba (西馬 ニコ, Saiba Niko), also known by her gaming tag "N", is a young tomboy and professional fighting game player who holds a grudge against Emu Hojo for defeating her in a Tekken tournament six years prior to the series. In pursuit of getting revenge on him, she appears before and latches onto Taiga Hanaya, much to his annoyance. Amidst the Kamen Rider Chronicle crisis, Saiba becomes Ride-Player Nico (ライドプレイヤーニコ, Raido Pureiyā Niko) to clear the game using her gaming strategies and discovers Emu's Bugster Parad is her real rival. After being nearly killed by the crisis' mastermind Masamune Dan however, she resumes her high school education, graduates, and goes on to become Hanaya's assistant.

Nico Saiba is portrayed by Reina Kurosaki (黒崎 レイナ, Kurosaki Reina). As a 12-year-old girl, she is portrayed by Noa Miyano (宮野 叶愛, Miyano Noa).

Tsukuru Koboshi

Tsukuru Koboshi (小星 作, Koboshi Tsukuru) is a video game developer for Gemn Corp.'s development team who spent five years developing the Rider Gashats. Following the apparent death of company CEO, Kuroto Dan, and Gemn Corp. suffering financial problems, Koboshi attempts to keep the company afloat by developing a new game called Ju Ju Burger. With support from his coworkers on the development team and the new CEO, Ren Amagasaki, they complete the game using Kuroto's private terminals, though Koboshi is infected with the Bugster Virus. The Burgermon Bugster emerges from Koboshi as a result, but he embraces it as a friend after seeing the monster is based on one of Ju Ju Burger's characters. When Burgermon inadvertently causes panic outside Gemn Corp. Koboshi and Emu Hojo intervene, but Kuroto kills Burgermon and confiscates the Ju Ju Burger Gashat in retaliation for someone creating a game without his permission. While mourning Burgermon, Koboshi is recruited by Taiga Hanaya to develop the Maximum Mighty X Gashat so Emu can defeat Kuroto. Following this, Koboshi eventually becomes the new CEO of Gemn Corp. and posthumously makes Burgermon a company mascot.

Tsukuru Koboshi is portrayed by Shohei Uno (宇野 祥平, Uno Shōhei).

Ride-Players

The Ride-Players (ライドプレイヤー, Raido Pureiyā) are civilians infected with the Bugster Virus who transform using mass-produced Kamen Rider Chronicle Gashats and initially wield Ride-Weapons (ライドウエポン, Raido Uepon), which function as a dagger and gun, until they steal the Gamer Riders' Gashats to access the corresponding Gashacon Weapon. As participants of the Kamen Rider Chronicle event however, defeated players face the risk of being turned into data saved on Proto Gashats and fueling the Bugsters' plot to eliminate humanity or dying from the Bugster Virus if they quit the event without having defeated an opponent.

Next Genome Institute

The Next Genome Institute (ネクストゲノム研究所, Nekusuto Genomu Kenkyūjo) is a transhumanist institute that conducted groundbreaking and innovative research on genomes via the Genome Project (ゲノムプロジェクト, Genomu Purojekuto), though their methods are considered unethical and rumors of them committing horrific experiments have spread. Six years prior to the series, the group was approached by Kuroto Dan to extract the Bugster Virus from Emu Hojo's body. However, this resulted in the creation of Parad while the scientists were infected with Game Disease, sent to the Game World to be reborn as Bugsters, and presumed missing. The group resurfaces in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider to steal the Proto-Gashats from a compliant Kuroto in order to create the ultimate life form.

Tōgo Kiyomiya

Tōgo Kiyomiya (清宮 東吾, Kiyomiya Tōgo) is a high school student and computer programming prodigy who developed the Hate Sate Puzzle (ハテサテパズル, Hate Sate Pazuru, Well Well Puzzle) video game and appears exclusively in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider. Due to his being a carrier of a new strain of the Bugster Virus, the Next Genome Institute kidnap Kiyomiya, but the latter is rescued by Kamen Riders Ex-Aid, Ghost, Drive, Gaim, and Wizard.

Tōgo Kiyomiya is portrayed by Akira Takano (高野 洸, Takano Akira).

Hatena

The Hatena Bugster (ハテナバグスター, Hatena Bagusutā) is a Bugster born from the data of the Hate Sate Puzzle video game who is armed with the Puzzle Rod (パズルロッド, Pazuru Roddo). First appearing in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider, he infects and manifests from Tōgo Kiyomiya before he is killed by Kamen Rider Ghost.

In the Kamen Rider Para-DX Hyper Battle DVD special, Kuroto Dan recreates the Hatena Bugster to serve as a boss for his adventure game, Nazotoki Labyrinth (ナゾトキラビリンス, Nazotoki Rabirinsu, Riddle-Solving Labyrinth). However, the latter is killed by Kamen Riders Ex-Aid and Para-DX.

The Hatena Bugster is voiced by Hiroshi Naka (中 博史, Naka Hiroshi) in Heisei Generations and by Katsuyuki Konishi (小西 克幸, Konishi Katsuyuki) in Kamen Rider Para-DX.

Foundation X researcher

An unidentified Foundation X researcher who appears exclusively in the web-exclusive special Kamen Rider Brave: Survive! The Revived Beast Rider Squad. He visits the Seito University Hospital to secretly provide them the Night of Safari Gashat in order to see how Emu Hojo would use its power. While Hiiro Kagami ends up finding and using it instead, the researcher eventually recovers the Gashat and deems the experiment a success before contacting his superiors to begin conducting research into other Gashats.

The Foundation X researcher is portrayed by suit actor Kazuya Okada (岡田 和也, Okada Kazuya).

Another Hiiro

Another Hiiro (もう一人の飛彩, Mō Hitori no Hiiro) is a version of Hiiro Kagami born from the latter's guilt over failing to save Eito Kirino capable of traveling back and forth between the world of the Ultra Super Hero Taisen video game and the real world who appears exclusively in the crossover film Kamen Rider × Super Sentai: Ultra Super Hero Taisen.

Utilizing a Gamer Driver and the Japanese role-playing game-themed Taddle Legacy (タドルレガシー, Tadoru Regashī) Gashat, Another Hiiro can transform into Kamen Rider True Brave (仮面ライダートゥルーブレイブ, Kamen Raidā Turū Bureibu) Legacy Gamer (レガシーゲーマー, Regashī Gēmā) Level 50. While transformed, he wields the FlamberSaber (フランベルセイバー, Furanberuseibā) flame-bladed sword.

Like the original Hiiro Kagami, Another Hiiro is also portrayed by Toshiki Seto.

Eito Kirino

Eito Kirino (霧野 エイト, Kirino Eito) is a closed-minded boy and programming prodigy who appears exclusively in the crossover film Kamen Rider × Super Sentai: Ultra Super Hero Taisen. Born without emotions, he was infected with a disease that slowly digitized him and came into Hiiro Kagami's care, but died after refusing to allow Hiiro to operate on him. Failing to see anything beautiful about the real world, Kirino created the Ultra Super Hero Taisen video game in order to destroy it. Through Hiiro, Emu Hojo, Poppy Pipopapo, and the similarly emotionless Naga Ray's efforts however, Kirino is able to experience emotions and smile for the first time.

Eito Kirino is portrayed by Riku Ōnishi (大西 利空, Ōnishi Riku).

Shocker Leader III

Shocker Leader III (ショッカー首領三世, Shokkā Shuryō Sansei) is the new leader of Shocker who can transform into his true form, the Oogumo Great Leader (大蜘蛛大首領, Ōgumo Daishuryō), and appears exclusively in the crossover film Kamen Rider × Super Sentai: Ultra Super Hero Taisen. After being defeated off-screen by past Kamen Riders, he takes refuge in the Game World before resurfacing in the present as a boss for the Ultra Super Hero Taisen video game's Ultra Shocker Taisen (超ショッカー大戦, Chō Shokkā Taisen) bonus stage. He is defeated by an enlarged Kamen Rider Ex-Aid and two duplicates of the Kyurangers' mecha Kyurenoh.

Shocker Leader III is portrayed by Diamond Yukai (ダイアモンド✡ユカイ, Daiamondo Yukai).

Goriders

Kamen Sentai Gorider (仮面戦隊ゴライダー, Kamen Sentai Goraidā) is a Kamen Rider/Super Sentai hybrid team who appear in the crossover film Kamen Rider × Super Sentai: Ultra Super Hero Taisen and a self-titled web-exclusive miniseries. Consisting of the red-colored Akarider (アカライダー, Akaraidā), the blue-colored Aorider (アオライダー, Aoraidā), the yellow-colored Kirider (キライダー, Kiraidā), the pink-colored Momorider (モモライダー, Momoraidā) and the green-colored Midorider (ミドライダー, Midoraidā), the team incorporates traits from the first Sentai, Himitsu Sentai Gorenger, and Kamen Riders 1 and 2 from the original Kamen Rider television series and transform via Gorider cards. In battle, the Goriders wield a finned, multicolored grenade called the Rider Hurricane (ライダーハリケーン, Raidā Harikēn),^{[lower-alpha 4]} which they primarily use to perform finishing attacks.

In Ultra Super Hero Taisen, Emu Hojo, Yakumo Kato, Masato Jin, Momotaros, and Shuichi Kitaoka become Akarider, Aorider, Kirider, Momorider, and Midorider respectively upon winning the Ultra Super Hero Taisen tournament.

In the Kamen Sentai Gorider miniseries, Emu transforms Kaito Kumon, Kazuma Kenzaki, Kiriya Kujo, Yoko Minato, and Kaoru Kino into Akarider, Aorider, Kirider, Momorider, and Midorider respectively to assist him in defeating a backup copy of Kuroto Dan and his monstrous ally Totema.

Totema

Totema (トーテマ, Tōtema) is a mysterious monster who appears in the web-exclusive miniseries Kamen Sentai Gorider. He was developed by Kuroto Dan to serve as the invincible final boss for his unbeatable game, as well as lure in five deceased Kamen Riders so Kuroto can use them to revive himself. Despite possessing the ability to reconstruct himself if he is destroyed, Totema is destroyed by Kamen Rider Ex-Aid and Kamen Sentai Gorider.

Totema is voiced by Kazuki Yao (矢尾 一樹, Yao Kazuki) while Ruka Matsuda, who also portrays Poppy Pipopapo, portrays his maid NPC disguise.

Machina Vision

Machina Vision (マキナビジョン, Makina Bijon) is a foreign video game company that develops advanced VR technology and cooperated with Genm Corp. in the distribution of Kamen Rider Chronicle in exchange for a Gamer Driver from Masamune Dan. However, their deal fell through after Masamune discovered Machina Vision CEO Johnny Maxima had no intention of upholding his end. A year after Masamune's death, Machina Vision hacks Genm Corp.'s servers to steal data on the Gamer Driver and Rider Gashats.

Madoka Hoshi

Madoka Hoshi (星 まどか, Hoshi Madoka) is a 7-year-old girl who requires daily treatments for her brain tumor, was transferred to the Seito University Hospital's care, and appears exclusively in the film Kamen Rider Ex-Aid the Movie: True Ending. Her father, Kagenari Nagumo, intends to save her by infecting her with the Gamedeus virus in order to transfer her consciousness to a virtual reality world in cyberspace. Despite Kamen Rider Ex-Aid's attempts to save her, she chooses to stay in the VR world with her father.

Madoka Hoshi is portrayed by Noel Moriyama (森山 のえる, Moriyama Noeru).

Akemi Hoshi

Akemi Hoshi (星 朱美, Hoshi Akemi) is Madoka's mother and Kagenari Nagumo's ex-wife who raised the former on her own.

Akemi Hoshi is portrayed by Miki Fujimoto (藤本 美貴, Fujimoto Miki).

Nebula Bugsters

The Nebula Bugsters (ネビュラバグスター, Nebyura Bagusutā) are Bugster/Smash hybrids that Kaisei Mogami created using Bugster Virus and liquid Nebula Gas samples.

Luke Kidman

Luke Kidman (ルーク＝キッドマン, Rūku Kiddoman) is an American esports professional who appears exclusively in the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending. He sees Nico Saiba as a rival despite being a fan of her.

Luke Kidman is portrayed by Harry Sugiyama (ハリー 杉山, Harī Sugiyama).

Black Parad

Black Parad (ブラックパラド, Burakku Parado), also known as Another Parad (アナザーパラド, Anazā Parado), is an alternate version of Parad that Kuroto Dan created after using his revived father, Masamune Dan, as a host incubator who appears exclusively in the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending. Upon Black Parad's creation, Kuroto has Saiko Yaotome reprogram the former to support him in acquiring human DNA and stopping CR from reviving Bugster Virus victims by replacing the original Parad. After fighting the original Parad, Black Parad is absorbed by Kuroto, who uses him to create the God Maximum Mighty X Gashat.

Utilizing a Gamer Driver and the double-sized Gashat Gear Dual Another (ガシャットギアデュアルアナザー, Gashatto Gia Dyuaru Anazā), Black Parad can transform into Kamen Rider Another Para-DX (仮面ライダーアナザーパラドクス, Kamen Raidā Anazā Paradokusu) Another Perfect Knock Out Gamer (アナザーパーフェクトノックアウトゲーマー, Anazā Pāfekuto Nokku Auto Gēmā).

Like the original Parad, Black Parad is portrayed by Shouma Kai.

Saiko Yaotome

Saiko Yaotome (八乙女 紗衣子, Yaotome Saiko) is a researcher of the Seito University Hospital's Regenerative Medicine Center, an authority on gene therapy, and the daughter of Michihiko Zaizen who researches methods for reviving Bugster Virus victims and appears exclusively in the V-Cinema, Kamen Rider Ex-Aid Trilogy: Another Ending. Using the Bugvisor G (バグヴァイザーG, Baguvaizā Jī) belt and its built-in life simulation game Bugster o Tsukuru ze! (バグスターを作るぜ!, Bagusutā o Tskuru ze!, I Will Make Bugster!), she intends to continue her father's work and avenge his death by working with Kuroto Dan to kill Bugsters in order to revive Bugster Virus victims. Upon learning Kuroto had used her however, she experiences remorse and helps the Gamer Riders develop a cure for Kuroto's victims during his attempt to destroy the universe and contribute to restoring Kiriya Kujo's humanity.

Saiko Yaotome is portrayed by Yurina Yanagi (柳 ゆり菜, Yanagi Yurina).

Kiyonaga Hojo

Kiyonaga Hojo (宝生 清長, Hōjō Kiyonaga) is Emu's father, the former president of a medical equipment manufacturing company, and the accidental creator of the Bugster Virus who appears exclusively in the Kamen Rider Ex-Aid tie-in novel, Mighty Novel X. Kiyonaga attempted to counteract the Bugster Virus before the Year 2000 problem, but Masamune Dan discovered his secrets and blackmailed him into turning Emu into a carrier for the virus. As a result, a guilt-ridden Kiyonaga severed all ties with his family. Following the events of Kamen Rider Ex-Aid Trilogy: Another Ending, Kiyonaga resurfaces as Kamen Rider Gemn to face and apologize to Emu as part of Kuroto Dan's Mighty Novel X game before Kuroto kills him.