Sachiko is a big-breasted honor student whose uniform is tightly stretched. She lives in a single-parent household, so she tries to be a good girl and spends her days studying, but behind her good-student facade she harbors a masochistic desire to be licked all over by a dirty man. One day, Nakata brings her drunk father home and sees her masturbating. He blackmails her and makes her have sex with him. Since then, she has become Nakata's sex slave and is trained in lewd acts...