Kuu Oonami is a Champion of humanity, one of the strongest warriors there exist in history, but calling her a hero would be a grave mistake. All that she has achieved was for the sake of destroying the Overworld, and who else to rely on but the ancient evil that tried to do just that?

Alone she plunged into the dark abyss without exit, and awakened the devil that once invaded humankind–but that devil was not as she expected.

This is the ridiculous story of a human who wanted to annihilate humankind.