Kumi Hon'amanuma, a college student, relocates to Kyoto to inherit her late grandmother's candy store. Upon arriving, she finds the store's attached house already occupied by three female heroes reincarnated from another world – Harami, Mai, and K – alongside their dog. Shortly after this discovery, Kumi is approached by the former demon king, who was unexpectedly reincarnated into the form of an elementary school student. This former demon king seeks Kumi's aid in collecting his scattered power fragments.