On the day before summer vacation, on the way home after school, the voices of a man and woman suddenly come from the gym storeroom. Inside, the beautiful homeroom teacher Riona is engrossed in an extramarital affair. A student discovers her weakness and attacks her, confining her in the gym storeroom. No one comes to rescue her in the school building during summer vacation. Riona is played with like a toy by several students. There are 11 days left until the new semester starts...