Ryouga Kamishiro  

Reginald Kastle, Shark, 神代 凌牙

Ryouga is one of yuumas close friends and rivals. initially, after being disqualified from the national duel circuit, ryouga was bitter and uncaring. he flaunted his power by taking the decks of those he defeated. however, following his defeat by yuuma in the second episode, and with his numbers taken away, ryouga returned to a more humble state. ryouga harbors intense hatred towards iv for setting him up to be disqualified and implying that he intentionally hurt his younger sister. upon learning this from iv himself, ryouga entered world duel carnival with a newfound coldness and brutality, considering yuuma an enemy.