In a world where vampires share a genetic makeup similar to that of humans, distinguishing them is difficult. Yet, a distinct difference exists: when one of these vampires, referred to by the general public as devils, sees human blood, they completely lose control. Ordinary girl Tsukasa Taira becomes the object of affection for vampire Shouta Akimura. To avoid hurting her, he has resorted to killing other humans to satiate his bloodlust. However, Shouta walks a thin line, risking a loss of control at any moment. To neutralize the potential threat, detective Yuuki Anzai intervenes to save Tsukasa from becoming Shouta's next victim. As he takes her home, Tsukasa finds herself enthralled by Anzai, who is also a vampire. Together, they begin a tenuous relationship that draws them into the depths of a vicious conspiracy, rampant with murder and intrigue.