In a world teeming with monsters, the hero party is formed for the purpose of defeating the demon lord. One day, the female hero was derided by the other party members, and with her feelings hurt, she decides to go out alone at night. However, she is assailed by a monster and her body poisoned by an aphrodisiac. When she loses consciousness... who should save her, but none other than the demon lord himself! The next time she regains her senses, the female hero finds herself in the demon lord's bedroom... and for some reason, he is offering to help her with her insufferable aphrodisiac problem... After which... the female hero ends up having sex with the demon lord. However, it would seem that the two are actually... ... ...?