Otonokizaka High School is in a crisis! With the number of enrolling students dropping lower and lower every year, the school is set to shut down after its current first years graduate. However, second year Honoka Kousaka refuses to let it go without a fight. Searching for a solution, she comes across popular school idol group A-RISE and sets out to create a school idol group of her own. With the help of her childhood friends Umi Sonoda and Kotori Minami, Honoka forms μ's (pronounced "muse") to boost awareness and popularity of her school.