Cross Academy is attended by two groups of students: the Day Class & 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 & Zero Kiryu are the Guardians of the school protecting the Day Class from the Academys dark secret: the Night Class is full of vampires! Zero is suspected of killing Shizuka Hio the pureblood vampire who murdered his family. Incensed the vampire senate sends assassins to Cross Academy to execute him. Will the Night Class intervene or will Kaname let Zero take the fall?