The loner Hayashi Itsuki is suddenly transported into another world, a world with magical girls who reside at an academy. However, humans are not allowed at the academy, and Hayashi has to avoid being caught. Hijinks ensue as he gets tangled up with various magical girls as the only guy at an all-girls school...not. He's caught, turned into a rat, and thrown into a cellar with a hungry snake. Hayashi is forced to survive in this fantasy world without having any magic abilities himself, all while starting off as a defenseless rat.