A decade ago, the protagonist Max emerged victorious over the malevolent Demon Lord. In an attempt to restore his strength, the Demon Lord entered a prolonged slumber. However, upon awakening, he finds himself transformed into a diminutive, cute version of his once fearsome self.
Intrigued by Max's current situation, the Demon Lord pays him a visit, only to find the renowned hero residing in a rundown, cramped apartment. Surprisingly, the Demon Lord decides to move in with Max, aiming to assist his former adversary in reclaiming his former might and transforming him into a formidable opponent once again!