Mikagura High School is a boarding school where each student must join an activity club upon enrollment, and then battle it out with other club reps using their own unique abilities. Naive freshman Eruna Ichinomiya enters Mikagura High School with dreams of beauty and fun, but soon becomes the representative of a club, and is immediately thrown into the fray. However, Eruna soon finds out that in the culture clubs, there is one cardinal rule ... and she's going to have to learn it the hard way.