Yuki Cross's earliest memory is being attacked by a vampire as a small child and rescued by another — Kaname Kuran. Years later she and vampire hunter Zero Kiryu serve as school guardians at Cross Academy, keeping the peace between the human Day Class and the vampire Night Class. Her childhood friend Zero has spent four years trying to stop his own transformation into a vampire and has finally lost that fight. Yuki works to help him control his bloodlust while simultaneously trying to recover her own missing memories — and growing increasingly certain that Kaname is withholding something important.