Name: 瀬戸康史 (せと こうじ)
Name (romaji): Seto Koji
Profession: Actor and Singer
Birthplace: Fukuoka, Japan
Weight: 52 kg
Star sign: Taurus
Blood type: A
Talent agency: Watanabe Pro
Koji Seto (瀬戸康史 Seto Kōji?, May 18, 1988) is a Japanese actor and singer. He is currently starring as the young medical student Shunta Matsumoto in the BeeTV Series GIFT. Koji was also the lead vocalist of the Band J-Rock Band TETRA-FANG. The lively and bright multitalent is nicknamed Setomaru (瀬戸丸) and one of the youngest members from the acting group D-BOYS.
Born in 1988 on the land side of Kyushu Koji grew up as the oldest child with two younger sisters. 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. The praised Drama and performance by Satoshi Tsumabuki inspired his wish to become an actor. After discussing this with his parents, they decided to support their son and enrolled him to a local acting school. 
After one year in training Koji was casted in 2005 as Makoto Kanno, the snobbish main antagonist of later D-BOYS-fellow members Yuya Endo and Kotaroh Yanagi, in the comedy TV Series Rocket Boys. Although the series was filmed earlier, it would take over six months until its broadcasting. Meanwhile, after the filming ended, his parents surprised their son with a letter that stated the teenager made it to the final round of Watanabe Entertainment´s 2nd official D-BOYS audition. With his interpretation of Fukuyama Masaharu´s song "Himawari" won Koji the Grand Prix 2nd Winner Award on 31 July 2005. He debuted as a Junior member just shortly afterwards in December at the 3rd D-Live Event - an entertainment show featuring only D-BOYS members. 
In Spring 2006, at the age of 17, Koji finally moved after constant commuting from his rural and idyllic hometown in Fukuoka to live by himself in the 1,100 km distant, turbulent Tokyo. Koji 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 the part of the hyperactive acrobatic tennis player Eiji Kikumaru in Tenimyu. In 151 performances the name Setomaru was established (the nickname was his own idea, by combinating his own surname (Seto) and Eiji's (Maru)) and took its place in the hearts of fans in Japan and all over the world until his Graduation alongside the members of the 3rd Seigaku-Generation on 9 September 2007. Koji 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. 
Koji's D-BOYS logo is a chameleon, in reference to his versatility. In late 2006 the young actor was chosen as Thursday's-face of OhaStar, a children's TV show airing live every morning on TV Tokyo. He co-hosted the show constantly, once a week together with Kōichi Yamadera, until the 28th April 2008. Seto-kun was not just a boy in an old-fashioned green uniform - he also had the ability to change his persona with the use of his "Miracle Glasses". This way, Koji was able to act out his part in 8 different ways. He was casted in spring 2007 as the dallying greenhorn Kyoichi Segawa, a young gentleman host in Happy Boys, and his first leading part. The drama followed Makoto Tateno´s script, which was published alongside the TV Series in Manga-form. Mangaka Tateno created the character design originally based upon the actors - a very rare occurrence. Right after this series, the teenager was offered his first starring role in a movie, as the meekly salesman Chibe-kun, who tries to deal with the yaoi passion of his girlfriend in the crazy comedy Tonari no Yaoi-chan, a self-parody movie based on a real-life blog that centered on the 801-chan phenomenon.
The part of Izamu Hayama in the touching feature film Tenshi ga Kureta Mono was his first cinema production in autumn 2007. Koji 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 protagonists, the young atelier and half-vampire Wataru Kurenai whose alter-ego is Kamen Rider Kiva. About the same time, Koji was chosen among 1000 competitors in an audition for the leading part as the rebel Hiroki "Hiro" Sakurai, in the TV series adaption of Koizora (after the bestseller book by Mika), making him the leading actor for two TV series filmed and broadcasted at the same time.
In early 2009, Koji started filming for the latest Ju-On movie Ju-On - Black Girl. He reprised his role as Wataru Kurenai for the first and last episode of Kamen Rider Decade, as well as in Decade: Final Chapter, the last part of the storyline. He starred then as the hotheaded Genius-Magican Satoru Okura in the Fuji TV Hit-Drama Atashinchi no Danshi as one of Maki Horikita's 6 sons. Afterwards he was playing the cheerful, but delusional junior Ariake Yamato in the drama adaption of the Hit-Manga Otomen. At the end of October, he finished filming for his starring part in the award-winning TV movie Rinne no Ame as the intellectually disabled Shuhei Mikami.  He is recently playing as Yuta Takenaka for the new TV series, Tumbling.