Live and Learn (1971)
Tetsuko (Eiko Yanami), a high school student, one day, forces Tsuneo, (Kei Wakakura), the brightest boy in her school, to make love to her after school is out and they are caught by the old school janitor. Tsuneo's mother, orders Tetsuko to pay for what she did to her son but Tetsuko blackmails her