List of One-Punch Man characters On an unnamed Earth-like super-continent planet, powerful monsters and villains have been mysteriously appearing and causing disasters. To combat them, the world's government has created a Hero Association that employs superheroes to try and stop the violent creatures and villains. Saitama is an unranked hero, hailing from the metropolis of City-Z, who performs heroic deeds for his own entertainment. He has trained himself and grown strong to the point where he can effortlessly defeat any opponent with a single punch. However, since Saitama became a hero for the fun of the experience, he has lately become bored with his superhuman power, and frustrated at the complete lack of strong opponents that can challenge him. Over the course of the series, Saitama encounters various superheroes, villains, and monsters.