The most grotesque pure love story begins! Kanji Todoroki, a boy who died in a quarrel. Airi, a childhood friend, presented herself to the devil, Aion, in order to save Kanji. The only wish of the devil is to "know human love." As a result, Aion turns into Airi and tries to nurture Kanji and gain his love. On the other hand, Kanji turns a fierce hatred on Aion who stole Airi ...