What's a World Without the Demon King?

There once was a demon king in the continent of Offiton, who was cruel and cruel. In order to defeat the devil, humans summoned the brave, and after the brave defeated the devil. People discovered that the hero's magic power was huge, so they used the hero as a battery to provide magic power. The former hero knew all this and decided to transform into a demon king and become the king of monsters. Conquer beauties, elves, succubi, harpies... From all races. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.