Yuuki Cross, who is cheerful, and Zero Kiryuu, who is gruff, serve on the disciplinary committee at Cross Academy. The academy contains two very distinct classes: the Day Class and the Night Class. Their duty involves maintaining order between the classes during their switch. Although this might not appear to be a particularly difficult task, the Day Class does not know the truth about the Night Class—their students, who are utterly gorgeous, are vampires. Ten years ago, Kaname Kuran, a Pureblood vampire, saved Yuuki from a vampire attack. Kaname now leads the Night Class, and Yuuki's position on the disciplinary committee lets her see him again, which makes her feelings for him grow complicated. Meanwhile, Zero holds a white-hot hatred for all vampires and believes they can never live in harmony with humans. However, a secret from Zero's past soon threatens the fragile peace of everyone at the academy, and things may never be the same again.