Otonokizaka High School, a traditional school in Tokyo, faces closure due to a lack of incoming students. When second-year student Honoka Kōsaka learns her beloved school will shut down after the current first-years graduate, she searches for a way to reverse its fortunes. Visiting the popular UTX High School with her younger sister, Honoka witnesses the dazzling performance of the school's idol group, A-RISE. Inspired by the crowd they draw and the attention they generate, she becomes convinced that starting her own school idol group is the only way to attract new applicants and save Otonokizaka.

Honoka persuades her two childhood friends, the pragmatic Umi Sonoda and the gentle Kotori Minami, to join her. Together, they form the idol group μ's, pronounced "muse." Their path is far from easy. Student council president Eli Ayase firmly opposes the idea, refusing to recognize them as an official club. They struggle to recruit additional members, facing rejection from the talented but reluctant composer Maki Nishikino, the shy idol fan Hanayo Koizumi, her energetic friend Rin Hoshizora, and the initially hostile third-year idol enthusiast Nico Yazawa. Each girl has her own insecurities and reasons for hesitating, and the early episodes focus on Honoka's persistent optimism gradually breaking down these barriers. A significant early arc involves the group preparing for their first concert, only to perform to an empty auditorium, a crushing setback that tests their resolve.

The narrative shifts as μ's finally reaches nine members and sets its sights on Love Live, a national competition to determine the best school idol group. This goal forces them to confront Eli's continued resistance directly. It is revealed that Eli, a former ballet dancer, initially dismissed school idols because of her own painful experiences with pursuing a passion. Through the quiet guidance of the vice president, Nozomi Tōjō, Eli comes to understand the sincerity of μ's efforts and eventually joins the group, bringing her discipline and experience. As μ's ranking rises, they must balance intense practice with studying for final exams to gain school approval for the competition. The season builds toward their performance at the school festival, where Honoka collapses from exhaustion, leading to a moment of crisis that forces the group to reconsider their priorities. Ultimately, their efforts succeed in generating enough attention to save Otonokizaka from closure, fulfilling their original goal just as they earn a place in the Love Live tournament.