"Akuma na Eros" is focused on Miu Sakurai, a high-school girl who is in love with her classmate, Shion Amamiya. Miu summons Satan through a book and wishes for Amamiya to fall in love with her, but Satan demands her virginity as the price. Satan's spell fails because Amamiya is Christian, and uses his powers to make disguise himself as Miu's elder brother named "Kai", and his crow familiar, Malphas, into a younger brother named Tsubasa. Satan demands her virginity on the day of Amamiya's love confession to Miu, but along the way Miu develops feelings for Satan.