Makoto Uda, a high school student, and his childhood friend Yuki Mika share a secret: Yuki possesses five distinct personalities. Despite this, they manage to live a peaceful high school life. That peace is shattered when an unexplained event divides their school into two factions—good and evil—by an unknown group. The classroom turns into a bloody battlefield where students are forced to kill each other. Each severed head earns a star, and the number of stars determines a student’s rank in this new brutal hierarchy. The students aligned with the so-called Pujuru alien side commit increasingly savage murders, led by a girl who already possesses sixteen stars. Blood, anger, and despair consume the school as Makoto and Yuki struggle to survive in a place where former friends become enemies and only the most ruthless can hope to live until the end.