Career
He played the part of the guitarist Eritate Kengo in the 2008 Kamen Rider Series, Kamen Rider Kiva. He was one of "Rajikaru""s 5 member and appeared from time to time on the NTV show. Afterwards he starred together with all Doctorate-BOYS in their first own television production "Doctor of Divinity-BOYS".He is one of the Doctorate-boys who holds an English proficiency and a bit Chinese.
In September 2008, it was announced that Kumai was leaving the Doctorate-BOYS, although he was still being represented by Watanabe Entertainment.
In February 2009 he was removed in the management of Watanabe Entertainment. His official profile linked in the Company"s website are now closed and not working.
He is now under Office Shuu Management. 2006 - Doctor of Divinity-BOYS Volume 1 - 6 (+ 1 Special Digital Video Disc) 2007 - Doctorate-Boys Stage Volume 1 2007 - Bacchigi LOVE & PEACE Digital Video Disc 2007 - Renai Shindan ~Unmei no Kodo~ Digital Video Disc (release date 19 December 2007) 1.
