Oyabon is a student of Momo and also old rival of Mighty. He and Mighty both entered the Bomberman Tournament but no matter how hard he tried, Oyabon couldn't beat Mighty. Later on in his life he opened his own dojo and is now followed by Kobon, his loyal student. His name is a pun on "oyabun", which in Japanese means "boss". The "bon" part of his name is most likely a derivative of "bomb" from "Bomberman." His signature bomb is the "Banchou Bomb", with "banchou" meaning "a leader of a group of delinquents". Despite his naming themes surrounding words associated with juvenile delinquents, Oyabon isn't one himself. It's probable that the names were chosen to show his leadership rather than be taken literally.