The male student protagonist Murasame is called to the other world Etanaria as a hero every night in order to fight the maou's army. Not knowing what to do with Murasame, the maou's army sent the succubus Miretto to his side.

Murasame goes back and forth between Etanaria and modern day Japan while falling to Miretto's temptation. But if Murasame yields to Miretto's lovey-dovey seductive techniques, his body will be trained and Etanaria will be ruined!