In 2000, at the age of 14, Kamiyama was part of D.A.N.K. (Daisuke Asakura New Kids), a performance troupe produced by
Daisuke Asakura. In 2001, he appeared on the audition program
Study Park!!, where he was selected as one of the members for the boy band
Run&Gun, later debuting on July 4, 2001 with the single "Lay-Up!" During his time with the group, in 2005, Kamiyama also released a solo song titled "Byū Byū Kuru Yasashisa wa" for Run&Gun's first extended play,
Hateshinai Tabi no Naka de... In 2007, Kamiyama was cast as Romeo in the stage play adaptation of
Air Gear. In the second installment he took over the lead role of
Minami Ikki after
Kenta Kamakari fell ill. He broke his arm during the second-to-last showing of the musical; however, he continued performing. In addition to this, Kamiyama also published his first novel,
Flying Melon, which was co-written with
Kosuke Yonehara. In 2014, Kamiyama left Run&Gun to focus on acting full-time. ==Personal life==