In a Japan infested with monsters, an academy was established to train Magical Girls as a countermeasure. A monster named Girlande infiltrates the school as a teacher under the alias Eiji Asaki. Everything seemed to be going smoothly until he caught the eye of a certain Magical Girl.

Her name is Hibari Hinanagi. It turns out they met ten years ago, and despite being a Magical Girl, she has become a "yandere" who is fanatically obsessed with Girlande (Eiji)! After she offers her cooperation, Eiji decides to take her along on his missions. However, this Magical Girl turns out to be a total klutz...!?