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! A war among vampires has started at Cross Academy, and even Day Class students are being attacked. Kaname finally reveals his hidden plan to Zero, and Zero must choose on which side he will fight. But in order for Zero to defeat the enemy, he will have to take part in an atrocious act...