Main

• Kanzo Hattori (ハットリ カンゾウ or 服部 貫蔵, Hattori Kanzō)

(voice: Junko Hori; drama actor: Kōtoku Nomura, drama voice: Kazuo Imakura, live-action film actor: Shingo Katori)

Hattori-kun, is the protagonist of the series, a little ninja who is named after his ancestor Hattori Hanzō. He is 11 years old and a skilled ninja despite his age who left his home in Iga to train in Tokyo, where he took up residence in the Mitsuba household. The show follows his many adventures and daily life living in modern Japan and his friendship with Kenichi Mitsuba. Both boys find a rival in Kemaki (Kemumaki in some dubs), another young ninja in Kenichi's class. Hattori-kun's main weakness is that he is terrified of frogs (Ranidaphobia) . He has strong beliefs on what makes a good ninja and reminds everyone of the same. Hattori-kun has signature swirls on his cheeks, wears a blue head covering at all times, and also has a quirk of saying ~degozaru or nin nin (ding ding in dubs) after almost every sentence. Hattori-kun has an ardent admirer, Tsubame. He wears blue coloured ninja robes with a red belt.

• Shinzō Hattori (ハットリ シンゾウ or 服部 心蔵, Hattori Shinzō)

(voice: Yūko Mita (1980s series), Etsuko Kozakura (2000s video games), Ryō Hirohashi (2000s video games), Yukiko Hinata (2012 series, various video games^[3]); drama actor: Shigeki Nakajō)

Shinzo is Kanzo's five-year-old younger brother who followed him to Tokyo. Being only an apprentice ninja he uses wooden weapons. His older brother Hattori is his role model. He can cry extremely loudly, stunning people and even causing them to faint. He helps Kanzo fight Kemumaki, sometimes using his loud crying to immobilise opponents. He wears red coloured ninja robes. His catchphrase is "shin shin".

• Kenichi Mitsuba (三葉 ケン一, Mitsuba Ken'ichi)

(voice: Masako Sugaya (1980s series), Akiko Yajima (2000s video games), Makiko Ōmoto (2000s video games), Tomomi Tenjinbayashi (2012 series, various video games^[3]); drama actor: Katsumi Takamiya, live-action film actor: Yuri Chinen)

A 10-year-old middle schooler who doesn't have much academic or athletic talent but enjoys photography. His greatest desire is to win the affections of classmate Yumeko, in the process of which he often gets into trouble with his rival Kemaki and convinces the hesitant Hattori to help him. He is not above tricking Hattori into lending a hand. Kenichi wears glasses and a cap.

• Yumeko Kawai (河合 夢子, Kawai Yumeko)

(voice: Runa Akiyama (1980s series), Rei Sakuma (2000s video games), Haruka Sato (2012 anime^[4]), Yuka Iwahashi (2012 series,^[5] various video games^[3]))

Yumeko-chan, is a classmate and friend of Kenichi's. Both Kenichi and Kemaki have unrequited crushes on her, causing a rivalry between the two boys. Yumeko sees Hattori and Shinzo as brothers. She is a pianist and hates bell peppers. Yumeko appears in an episode of Perman as a cousin of Michiko. She wears a pink long sleeved dress and has her hair in a short cut with bangs.

• Shishimaru (獅子丸)

(voice: Kenichi Ogata)

Is a ninja dog living with Kenichi, who came along with Kanzo and Shinzo Hattori. He is often lazy and stubborn. Along with Shinzo, the two of them wind up doing mischief and creating trouble. He has an attack technique of turning in a fireball when provoked. He also has the ability to change form into any other animal. His fur is curly and yellow. Shishimaru's ninja mark on his forehead is very important for him as it is an identification of him as a ninja. He loves to eat all kinds of delicious treats, especially a fish sausage, or chocolate roll.

• Kemuzou Kemumaki (ケムマキ・ケムゾウ, Kemumaki Kemuzō)

(voice: Kaneta Kimotsuki (1980s series), Masato Nishimura/Mazin (2000s video games), Kazuki Ogawa (2012 series, various video games^[3]), live-action film actor: Gorie)

Is the antagonist of Ninja Hattori-kun. The 11-year-old ninja comes from the Koga village and hence is a sworn rival of the Iga native Hattoris. He lives alone in a small apartment with his ninja cat Kagechiyo. As per the Koga rules, his ninja identity is a secret, with only Kenichi and the Hattoris knowing about his dual life while he attends middle school as a normal student. His parents' whereabouts are unknown, but his mother is noted several times in the series, and once visited him while he was sleeping to cook him a meal. Kemaki is shorter than Kenichi but much better at school and sports than him. He isn't as good a ninja as Hattori-kun but never gives up trying to beat him. Despite being the main antagonist, he is actually a nice but lonely boy who sometimes helps out his rivals. Kemaki strongly adheres to his clan rules of never using ninjutsu for criminal acts, going so far as to temporarily excommunicate Kagechiyo for stealing an ice cream. He wears green colored ninja robes, is brown skinned and has his hair is a short ponytail.

• Kagechiyo (影千代)

(voice: Eiko Yamada (1980s series), Kazumi Totaka (most scenes; 2000s video games), Asako Kozuki (some scenes; 2000s video games), Ai Fukada (2012 series, various video games^[3]))

Is a talking ninja-cat of the Kōga-ryū clan. He serves as the supporting antagonist in the series. Usually, Kemumaki assigns significant tasks in his plans for Kagechiyo to carry out, but he often fails to succeed. This is because he doesn't receive enough training from Kemumaki and is often seen sleeping on the streets. Hattori notices him several times. He has a rivalry with Shishimaru. His fur color is black and white. He typically hides in the Mitsuba house to eavesdrop on Kenichi and his friends' plans, and afterwards, he informs Kemumaki about them, making him well-suited to being a spy. At times, he resents Kemumaki for his strictness and imagines living a life of luxury as a normal cat in some episodes. He enjoys eating fish. He obtains an attack of static electricity by rubbing a shiny metal plate against his back. If he uses this attack too much, it will drain his energy, and he will feel weak.

Supporting

• Aiko-Sensei (愛子先生)

(voice: Yōko Kawanami (1980s series), Asako Kozuki (most scenes; 2000s video games), Taeko Kawata (some scenes; 2000s video games), Ai Fukada (2012 series, various video games^[3]))

One of Kenichi's teachers. Koike-sensei has a crush on her. The subject she teaches is unknown. Though in many episodes she is shown teaching the class music.

• Koike-Sensei (小池先生)

(voice: Issei Futamata (1980s series), Toru Yoshida/Yoshibon (most scenes; 2000s video games), Jun'ichi Kanemaru (some scenes; 2000s video games), Hayato Nakata (2012 anime^[6]), Tomokazu Yajima (2012 series,^[7] various video games^[3]))

Kenichi's teacher, also appears as a ramen chef in Obake no Q-tarō. He is caricatured after animator Shin'ichi Suzuki.

• Kentaro Mitsuba (三葉 健太郎)

(voice: Yuzuru Fujimoto (1980s series), Masato Nishimura/Mazin (2000s video games), Eiji Yanagisawa (2012 series, various video games^[3]); drama actor: Teizō Muta)

Kenichi's father. He usually smokes and comes from his office late in the evening. He likes eating and golf a lot. Though a rather plump man, in some of the episodes, his size seems to change, going from stouter to slimmer. He gave Kenichi his name, hoping for his son's good health.

• Taeko Mitsuba (三葉 妙子)

(voice: Yukiko Nashiwa (1980s series), Asako Kozuki (2000s video games), Miwa Kitahara (2012 series, various video games^[3]); drama actor: Chiharu Kuri)

The mother of Kenichi. She is a slim housewife who is busy keeping order of a house inhabited by six, including Shinzo who often wets his futon. She likes Tsubame and thinks that Kemaki is a good boy (not knowing of his ninja identity and pranking habit). Kenichi constantly stresses her out with his bad grades and his preference for playing over studying, making her lecture him.

Other

• Professor Shinobino (シノビノ博士, Shinobino Hakase)

(voice: Reizō Nomoto (1980s series))

A professor who lives in the United States (USA) and invented Togejirou.

• Togejirou (トゲ次郎, Togejirō)

(voice: Hiroko Maruyama (1980s series))

A cactus having supernatural powers is sent by Professor Shinobino from the United States. Shisimaru does not like Cacto-chan and loves to compete with him.

• Tsubame (ツバメ)

(voice: Fuyumi Shiraishi (1980s series))

A.k.a. Tsubame-ko, is a kunoichi and classmate of Hattori-kun. She likes Hattori and always wishes to marry him. She has a dislike for Kemumaki and Kagechiyo. She wears pink coloured ninja robes. She seems to own a recorder, a clarinet, a flute, a piccolo and a bassoon, five woodwind instruments.

• Isa Yohi

A koga ninja girl who is a senior of Kemumaki and a frenemy of Hattori. First she start to fight Ninja Hattori. Later She also helps Hattori and His Friends. This character was appeared in 2012 Anime only.

• Robert

An american ninja who is a student of Ninja Hattori. He learns only wrong Ninja techniques. Later these become very useful to him.

• Saizo

An iga ninja boy who tries to achieve primary school certification. His power is creating a cloud and using for a transportation.

• Gosuke

An iga ninja boy who tries to achieve Primary School Certification. His power is do anything within few seconds.

• Surasuke

An iga ninja boy who tries to achieve Primary School Certification. His power is speed.

• Old Grandma

Saizo Gosuke and Surasuke's adopted grandmother. She like them and take care him as grandsons. She also helps Hattori and Kenechi.

• Kittu

Kiyo's Little Brother Cat. Kittu likes Kiyo and thought as a Big Brother. Kittu uses Ninja techniques also. Kittu mostly appears in the 2012 anime.

• Momombe

An iga ninja squirrel who is a childhood friend of Shishimaru's. Momombe uses more ninja techniques than Shishimaru. Momombe mostly appears in the 2012 anime.

• Inspector

A sub-inspector of Mitoriquaika City. He likes Hattori because Hattori and his friends help him to catch the thieves. He mostly appears in 1981 anime.

• Jinzo Hattori (ハットリ ジンゾウ)

(voice: Tadao Futami (1980s series))

Hattori-kun and Shinzou's father. He also appear in Perman, when he fights with Perman.

• Jippo (忍者怪獣ジッポウ, Ninja Kaijū Jippō)

(voice: Junpei Takiguchi (1980s series), drama voice: Hiroko Maruyama)

A giant turtle monster ninja. He and Hattori are ninja partners.

• Tai-chan

A baby who uses ninja techniques perfectly. He learned ninja techniques who taught by Hattori Kanzou. Tai-chan is mostly appeared in 2012 anime.

• Toko

Yumeko's pet. Toko always likes Kenichi. So, it became a friend to Kenichi. Toko is appeared in 2012 anime.

• Mimicky

Kiyo's enemy and Kemumaki's old pet. He copies everyone for his hungry. He ate free food who given by his owner who copied by Mimicky.

• Ninja Eagle

An iga valley's messenger. It gives a message who was given by an iga valley's members to Hattori.

• Pet Teacher

Kenichi's pet teacher was appeared in few Episodes of 2012 Anime.

• Mokamaru

He is a high tech ninja. Hattori's old enemy. He uses computer ninja techniques to attack Hattori. He appears in the movie Ninja Hattori-kun: Nin Nin Furusato Daisakusen no Maki (Ninja Hattori - Home Town).

• Green Frog

Kemumaki's pet. Kemumaki use this pet to beat Hattori's brave. Green frog is appeared in 2012 anime.

Manga

The first manga series was published in Kobunsha's Shōnen in 1964 and ended in 1968. A second manga series was published by Shogakukan in various kids magazines like CoroCoro Comic, Televi-Kun and others from 1981 to 1988.^[8]

TV drama

It was made into a live-action TV drama. Aired from 1966 - 1968. This was a work of special effects sitcom. This drama was aired on TV Asahi and was divided into 2 seasons, first season aired from 7 April to 28 September 1966, second season aired from August 3, 1967 to January 25, 1968. Each season consists of 26 episodes, in total 52 episodes from 2 seasons.

Anime

Live-action film

A live-action film entitled Nin x Nin: Ninja Hattori-kun, the Movie was released in 2004.