Satoru better known by his hero alias Mumen Rider is the C-Class Rank 1 professional hero of the Hero Association. Satoru is a young man of average height and weight. He wears an armored suit, with brown armor covering his torso and shoulders. He has a black leather suit under the armor, black gauntlets, and knee pads. He also has a green bicycle helmet and dark-shaded goggles. Underneath his helmet and shades, he has short, brown hair and oval-shaped glasses that obscure his eyes.