From birth to school days

Born on July 30, 1987, in Myoko-Kogen, Nakakubi-gun, Niigata Prefecture (now Myoko City, Niigata Prefecture) as the eldest son.^[3]

As a child he longed to be a baker because of his favorite food, bread. The first video he uploaded to YouTube as "SeikinTV" was "Morning is Bread.^[4]

In 2000 he entered a local junior high school, where he was a member of an a cappella group from the first year of junior high school and also joined the brass band, playing the trombone.^[5]

At high school he switched from the brass band and joined the ski club,^[6] where he placed fourth in the inter-high school ski jump competition. His younger brother Hikakin recalls Seikin in high school, "Unlike me, he studied for an hour every day, even before a test.^[7]

After graduating from high school he moved to Tokyo and entered the Faculty of Letters at Senshu University.^[8] However, he realized that it was not the path he wanted to take and dropped out.^[9] After that, while searching for his own path, he found a job at an electric power company, but he resigned because he wanted to get good grades and could not stand the power harassment and sexual harassment from those around him.^[9] Then, in 2012, he started his YouTube activities as a YouTuber.

As a YouTuber

In 2012—under the influence of his younger brother Hikakin, who was already expanding his activities as a YouTuber on the video website YouTube—Seikin created the "SeikinTV" channel on YouTube.

On March 2 of the same year Seikin uploaded "Morning is Bread," a song written and performed a cappella by Seikin himself, marking his start as a YouTuber. He initially called himself an "a cappella musician," and the name "SEIKIN" came from a suggestion he made to his younger brother HIKAKIN: "I'm Hikakin, so why not Seikin?^[10]

On December 25, 2014 he reported in his video that he had entered into a marriage and married a civilian woman of the same age with whom he had been dating for two and a half years.^[11][12] Two years later, in 2016, they had a wedding ceremony that also included a honeymoon in the state of Hawaii in the United States.^[13] He commented that the secret to a happy marriage is to "think of the other person's feelings before your own." He commented.^[14]

In 2015 he and his younger brother Hikakin released their first single "YouTube Theme Song" as "Hikakin & Seikin," and it was the first single to reach No. 2 on the iTunes album ranking at the time.^[15] The song was originally inspired by the video "YouTube Theme Song" that Seikin uploaded in 2012.^[16]