Magical Girl Apocalypse

High-schooler Kii Kogami is 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. A little girl clad in gothic lolita attire appears at school and starts to gruesomely bludgeon, dismember, and mutilate all who cross her path.