The story is set in the Grazio Empire, the last stronghold of humanity. Humans are on the brink of annihilation, and the planet has been almost completely colonized by demon invaders. Holy Knight Levillis knew that the violence and chaos was an omen of the resurrection of the Demon King, who was killed and sealed a long time ago. She and a few of her minions set out into demon territory to kill the King and save the human world...