Cross Academy is attended by two groups of students: the Day Class and the Night Class. At twilight, when the students of the Day Class return to their dorm, they cross paths with the Night Class on their way to school. Yuki Cross and Zero Kiryu are the Guardians of the school, protecting the Day Class from the Academy's dark secret: the Night Class is full of vampires! With Kaname missing, Yuki must now step in as acting head of her clan to maintain the fragile peace between the human and vampire societies. Will she be able to regain the trust of the vampire aristocrats, much less Aido?