"I'm just a guy who's a hero for fun. I do not lose. And the surface... is guarded by me!"

Saitama is a bald, ordinary-looking man with a thin, but well-built physique, and is of average height and weight. Saitama initially had spiky, black hair, but claims to have lost all of his hair suddenly and prematurely as a result of the toll taken on his body by his intense hero training.

Initially just a hero for fun,[4] he later registers to be a professional hero for the Hero Association,[5] and defends his home in Z-City from Mysterious Beings, Villains, and other threats.[6] Under the Hero Association, he is assigned the hero name Caped Baldy (ハゲマント, Hagemanto; Viz: Bald Cape),[7] and is currently B-Class Rank