AKB48's #1 bishoujo, Watanabe Mayu aka "Mayuyu", has a huge secret. Her true identity is the 38-year-old (!!) Usa Shijimi, works herself to the bone between teaching literature at the super-delinquent school, Mubou Metropolitan High School, and doubling as an idol! While she's somehow getting by without being revealed, a shocking situation occurs...!? What will happen to Mayuyu!!