Sou Kurosaki has a single objective in mind: to lose his virginity. Sou is exhausted by his romantic interests constantly being taken by his childhood friend, Kazushi Haita, who ridicules Sou's claim of finding a superior girl to those Haita has stolen by asserting that Sou would need to find a non-human girl. Choosing to do exactly that, Sou searches for an otherworldly beauty to achieve his goal. After several attempts, the boy succeeds in summoning the succubus Kogure Deimon, but soon discovers that the attractive red-haired girl he summoned is actually a boy. Making a quick escape, he rushes home, only to discover that his so-called cousin—who turns out to be Kogure—is staying over for an unspecified duration. Unable to return to his own world until his duty is completed, Kogure integrates himself into Sou's daily life, determined to take his virginity by any means necessary.