The Hero from Another World - One-Punch Man x RWBY

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.