His childhood dream of becoming a vet changed suddenly with the end of his Junior High School time, when he watched with 15 years the TV series Orange Days.

Seto starred together with all his fellow D-Boys members in their first own TV production "DD-Boys" and won, at the same time, the audition for Eiji Kikumaru in Musical: The Prince of Tennis and played him until September 9, 2007.

He and his stage partner Yukihiro Takiguchi were honored with a Best Actors Album and praised by the creator of the original work Takeshi Konomi as perfect cast.

He then co-starred in winter 2007 with Aya Ueto and Yo Oizumi in his first Golden Time TV series Abarenbo Mama as a kindergarten teacher.

From January 2008 to 2009 he starred as one of Toei's Tokusatsu Heros, the young violinist and half-vampire Wataru Kurenai, the protagonist in Kamen Rider Kiva.

In the spring TBS TV series Tumbling, Seto is starring as Yuta Takenaka, captain to the boy's rhythmic gymnastics team at Karasumori High, alongside Yusuke Yamamoto again.

In 7 August 2020, Seto married his costar in TV dramas Hope: Kitai Zero no Shinnyu Shain and Perfect World, Mizuki Yamamoto.