The protagonist, Hatase Hibiki, meets a young girl in the yard of an abandoned house next door, who is lost and crying. Little Hibiki tries to comfort her, and notices she is hurt, so he licks the blood from her wound and bandages it. Then the guardian of the young girl appears and takes her away, as she tells Hibiki that she will not forget him. Now Hibiki is in high school, and one day as he's walking to school with his neighbor and childhood friend, Miu, a girl suddenly falls from the sky before them: she is Melissa, princess of the demon world, and she claims that Hibiki is her fiance, because in the demon world tradition, when one drinks the blood of another it is a proposal for marriage. It's not long until Melissa's rival from the demon world, Emile, follows her to the human world, determined to steal away Hibiki from her, and Melissa's dense chosen fiance, Alfred, also appears, set on getting his honey back.

[From Boy's Love Games Headquarters]