Mankind, who broke the peace treaty with the demons and declared war, has been defeated. Civilization has been annihilated and mankind is walking the path of decline, while the demons have become the new masters of the work. The "Demon King" stands at the peak of all demons, but the Demon King's only wish is to have their life after work?? The sweet and bloody romance of a level-headed warrior and a demon king who wants to die!