Cage (Suehirogari)

In an empty classroom, a masked blackmail group trains traumatized teacher Mayuko as a "student-serving body," inducing painful near-orgasms amid her resistance and threats to expose her sister. Mayuko reveals a parallel blackmail by Class 3-B upperclassmen, hinting at alliances as a student resistance forms among second-years planning to alert seniors. Meanwhile, at the equestrian club, Reika, Minako, and Seki prepare for a high-stakes "Derby" race where the loser becomes the winner's pet to free a captive teacher, as Mayuko endures confusing arousal from horse motion during training.