Tsukasa, a college student, is rescued from an attack by a devil, one of many vampires that can blend in among the human population. Anzai, her savior, is a half-devil who exploits his supernatural gifts as a member of a shadowy police task force that specializes in devil-related crime in Tokyo. As Anzai continues to keep guard over Tsukasa, the two quickly forge a tentative bond—one that Anzai fears will test his iron-clad rule of never drinking human blood…Anzai, half vampire, and Tsukasa, a normal school girl. Vampires seem to be living among humans. Of course the government does not know of their existence, because their appearance does not differ from humans. They also do not need to drink blood, but when they get a craving or get angry, they can become uncontrollable monsters.