When a dark lord finds an abandoned and unhappy noblewoman in his forest, he takes her in and decides to spice up her life with naughty deeds.

In a city ruled by a trading card game, Teruto aims to defeat the King, whose downfall grants any wish. He and Sakura join the Rebuild battle to forge the "Key" and challenge the King for their desires.

The story of Saitama, a hero that does it just for fun & can defeat his enemies with a single punch.