Gyosutoma is a piranha monster working for the Dogma Kingdom and an antagonist in Kamen Rider Super-1. He was hiding in Raigyon who served as a decoy for him.
He was originally Ooichi Taketo, a new local immigrant to Tokyo who started a dojo and took in child ruffians as disciples for him to teach Gai Ryuken, a martial art technique that upholds killing your opponent. By spreading his teachings and recruiting children all throughout Tokyo, he planned to indoctrinate the people to Dogma's values. He gained his reputation by ruthlessly beating a restaurant freeloader and a reckless biking gang, claiming that he seeks for justice that the police are incapable of dealing.
By the time he bested Kazuya in human form with his technique he has already established his own permanent police force and captured students to assort the weak from the strong as potential Dogma converts. Gyosutoma has a hook hand and displays proficient martial arts being able to one handidly defeat all his disciples. His only power is his "Gyosutoma Kousen", a red plasma beam that either hypnotizes or fully incapacitates his enemies bodily functions. He was destroyed by Super-1's Super Rider Plum-blossom Two-step Kick.
He was later revived as part of the Dogma Revenge Corps and destroyed by Skyrider.