A distress message came through Akihiro’s computer. The Mohorovi Chicchi Delinquent Squad immediately began searching for the sender, but… Beneath the old, now storage-like school building of a junior high perched on a cape lies the secret base of the Mohorovi Chicchi Delinquent Squad. Four middle schoolers, including Mio Umi, take on mysterious rumors and strange incidents!!

Keiko Mitamura is a popular woman regardless of gender. Since she was a student, she is a hard worker and has a poor family environment, but she goes on to a national university with the expectations of her mother. Her job is going well at the pharmaceutical company where she works, and she fell in love with her boss, Kazuhiko Tokito, and got married. She just seemed like she was living a smooth sailing life. But when she was in high school, she had a secret dating partner around her. After Keiko goes on to college, the two of them are accelerating their passing. An incident that happened one night begins to cast a shadow on Keiko's life.