After working as a teacher for over ten years and becoming the head of her grade, female teacher Keiko Okumura (Hojo) one day encounters a female student crying on the street. When she approaches her, the student says, 'I was groped on the train.' It seems there have been other victims as well. Keiko, with her strong sense of justice, becomes enraged by this despicable act and decides to start patrolling trains to protect students. Amidst the crowded train, Keiko keeps an eye on her students. However, unbeknownst to her, a suspicious figure has crept up behind her and is reaching for her lower body…
