Mito Yamamoto is a handsome man, so much so that women flock to the restaurant where he works every day. When the owner decides he has had enough, he fires Mito, leaving him unemployed and homeless. Shortly after, Mito stumbles upon a cafe and cuts his hand on broken glass. A strange man named Ruka Saotome takes Mito aside, ostensibly to tend to the injury, but instead licks the blood away, remarking that it tastes disgusting before asking Mito to leave. Later that night, Mito accidentally slips off a building's roof and is caught by Ruka, who reveals himself to be a vampire. Ruka explains that a man's blood tastes disgusting, and the blood of someone unloved has an even worse flavor. However, Ruka cannot drink from girls, so he has been looking for a beautiful boy to become his thrall. He proposes that Mito fill this role and allow Ruka's affections to "ripen" his blood. Mito accepts and begins living with Ruka in the Hijirigaoka Boys' Academy dormitory. However, there is just one problem in all this: Mito is actually a girl!