Masayuki Nono

Channel all anger into one fist. A tale of unstoppable revenge action. ​Seventy years ago, dungeons suddenly opened across the world. Inside them, humanity discovered Mana, a substance that drastically accelerated human evolution. ​One day, the protagonist Seishiro rescues a woman inside a dungeon. She is an Oni, a high ranking class embedded with superior Mana. Over time, the two build a bond that serves as a bridge between humans and Oni, completely unaware that this very woman would betray him and strip away everything he ever held dear.

The protagonist, who was once said to be the strongest tactician in the human army, is killed by a plot by an aristocrat. Moreover, the nobleman is said to be living a rich life without being punished. “This world is wrong!” The protagonist, who was reincarnated as the demon king's lieutenant, punishes the high-ranking nobles who live in solitude, and in order to create a new world, he leads a small army of soldiers and defeats the high-ranking nobles, heroes, and stupid bosses.