Vampire knight, vol. 18 (Viz Media)

Cross Academy is attended aby 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! Yukio and Zero team up to go after Kaname. Yuki and Kaname fight each other in the headquarters of the Hunter Society while Sara tries to control Zero through her blood. The female progenitor's origin metal intervenes, and Yuki realizes there is only one way to stop Kaname...