Serious and strict teacher Anna has always maintained firm discipline, even with delinquent students. But her stern attitude has bred resentment among the students, creating an unspoken hostility between them. One day, while riding the train, she is suddenly groped by a molester and, unable to cry out, is left exposed and defenseless. This incident is no mere accident—it marks a turning point in her life. A delinquent boy who happened to be on the same train secretly records the entire scene. Using the footage as leverage, he begins blackmailing Miss Anna. From the next day onward, she becomes a plaything for the students. The once strict teacher, who wielded authority over her pupils, now finds herself dominated by them—an ironic downfall.