The school festival at Narutani Uta High School, where Momo and her friends attend, has begun. Momo was excited, but everything changed when her senior idol, Taki Yuuen, showed up. Using their previous "debt" as leverage, Taki pressures Momo into spending the entire festival period on dates with her. To make matters worse, a trouble arises during one of the festival events, and Momo faces a significant challenge as an idol...!? This is the third installment of the new century idol story!