18+ Himitsu no Akuma-chan

Sou Kurosaki has one goal on his mind: to lose his virginity. Sou is fed up with his love interests constantly being stolen by his childhood friend Kazushi Haita, who mocks his declaration of finding a much better girl than the ones Haita has stolen by stating that Sou would have to find a non-human girl. Deciding to do just that, Sou seeks out some otherworldly beauty to attain his goal.

After several attempts, the boy manages to summon the succubus Kogure Deimon, but soon realizes that the attractive red-haired girl he summoned is actually a boy. Quickly making his escape, he rushes home, only to find that his so-called cousin—who turns out to be Kogure—is staying over for an undisclosed amount of time. Unable to return to his world until his duty is fulfilled, Kogure integrates himself into Sou's daily life, determined to take his virginity by any means necessary.