Kainuma Ryusei (海沼流星) is a Japanese singer and rapper. He's a member of the group BALLISTIK BOYZ. He was selected to join the group after participating of EXILE Presents VOCAL BATTLE AUDITION 5 in the rap section.
He is an EXPG Omiya graduate.
Kainuma is half-Brazilian (as part of his mother) and half-Japanese (as part of his father).
Due to Kainuma's mother being Brazilian he was educated in Portuguese and can speak and write fluently due to that.