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!

Kaname, the pureblood vampire, has kept to his room since learning of Yuki and Zero's forbidden act. However, the arrival of Ichijo's grandfather brings the entire Night Class together to greet one of the oldest vampires on the senate. Ichijo's grandfather says he's there merely to visit his grandson, but he's out for Kaname's blood.