High-schooler Kii Kogami is stuck in a rut, loathing the monotonous doldrums of his everyday life. If only something exciting were to happen, something magical. As fate would have it, Kii is about to get his wish, but in a way more terrifying than anything he could have imagined. When a little girl clad in gothic lolita attire appears at school and starts to gruesomely bludgeon, dismember, and mutilate all who cross her path, while chanting the mantra "Magical Girl" under her breath, the school devolves into a state of bloody chaos.