A high school student called Ranko is attacked by a vagabond on school grounds late one afternoon. Her beloved teacher Sayuri rescues her, only to take her place as the victim. Ranko tries to get help from a piano tuner who is just leaving the school. They eventually find Sayuri and her attacker in a classroom, but the man refuses to go in and save her, saying to do so would risk her life. She is raped, and after the vagrant shoots his load and shuffles off, they clean Sayuri up and agree never to speak of what happened. Not long after the incident the piano tuner offers Sayuri a ride home from school, abducting her in the process and imprisoning her in his basement. As he subjects her to various forms of sexual torture, Ranko manages to figure out where she is being held – but risks being captured and violated herself.