Kii Kogami is looking for excitement in his life when a girl clad in gothic attire begins bludgeoning, dismembering, and mutilating all in her path while chanting the mantra "Magical." The high schoolers are terrified but even moreso because the girl's victims reanimate and join her in the rampage as her minions. What will be left of the world outside, even if young Kii escapes the high school?