Meet (Y/N), the most powerful hero on earth... that no one has ever heard of. He's done it all, slay monsters, avert disasters, and save the planet and if there is one thing he's learned is that he REALLY wants a break. After deciding to have a normal life, (Y/N) has chosen to finish high school. And what better place to have a normal school life than Honnouji Academy!!!! Anywhere... Literally anywhere else.

Y/N, an inter-dimensional hero. Y/N has become a complete legend in thousands of dimensions. Whether it is facing a monster, a disaster, a god, or other horrors, Y/N would always emerge victorious. Undefeated, unmatched.... Unbelievably tired. After spending much of his life fighting evil, Y/N wants nothing more than to return home. Of course as a reward for his heroism, he was sent to his home dimension, Earth.... Right?...

The cabbage was supposed to be forty percent off in the supermarket. Instead, a towering, multi-limbed nightmare tore through the produce aisle, screaming about cosmic supremacy and shattering the fluorescent lights. Deeply annoyed by the threat to his grocery budget, Saitama, as usual, ended the crisis with a single, unceremonious punch. He didn't expect the impact to tear open the fabric of reality. Now, he is stranded in a strange world where the moon is shattered, the local currency is useless, and black monsters called "Grimm" roam the wilderness. To make matters worse, the people here fight using bizarre spiritual shields and unique superpowers called "Aura" and "Semblances", concepts that mean absolutely nothing to a guy who just did a lot of push-ups.