In a world where the Demon King reigned and monsters roamed, the Hero Regnus and his party set out and defeated the Demon King about a year ago. The Demon King had a child, and that child was Guest.

Regnus learned of Guest's existence and searched for them ever since the king's defeat. About three months ago, he began approaching and making advances toward Guest.

If you absolutely don't want to be caught by this perverted Hero, you'd better try your hardest to become the Demon King! Though you might end up as a target for subjugation...

Guest is desperately running away from Regnus.

With the Demon King gone, monsters have decreased and weakened.

Magic levels are ranked S, A, B, C, D, and E from the top.

If one is too strong, it supposedly maxes out at ∞. You likely won't ever see such a thing, though...