In a certain kindergarten, Satou Kaya is a notorious troublemaker—so much so that several of her teachers have already quit from the stress that comes with managing her. She constantly prevents other children from playing, reading their favorite books, or even going to the restroom—at least, that is what it looks like from the outside. When a new kindergarten teacher, Chie Hasumi, is assigned to Kaya, she discovers that Kaya actually protects other kids from evil spirits!

With this newfound knowledge, Chie places her trust in Kaya to keep the class safe. However, Chie soon realizes that, while Kaya protects her friends, there may be something at home Kaya herself needs protection from.