In Tokyo's Chiyoda-ku is the traditional school Otonokizaka High. Second year student Kosaka Honoka discovers the school will be closed in three years. In order to avoid being closed, the school must increase its number of prospective students.

Honoka and friends form a school idol group to entice more students to attend. When pointed out their group could have the opposite of their desired effect, Honoka becomes dispirited.

Honoka's group idol name is "µ's" and the group debuts their first song. Their popularity grows at school, and they have their first concert.