Mumen Rider is the #1 Class C Hero in the Hero Association. He has a strong sense of justice and will fight all who threaten the peace, even if they outclass him, including the Sea King and Garou. He is one of the few people that acknowledges Saitama's strength, crediting him for beating the Deep Sea King. Although he can move up to Class B, he is very critical of himself, saying he doesn't deserve it. Mumen Rider is a true hero, rushing out to save people during the Boros invasion at the risk of his own life.