Soapland owner Samejima runs a hidden business procuring, selling, renting, training, retraining, and buying sex slaves. One day, a wealthy client orders a new woman. Samejima targets Mei, an office worker who lost both parents in an accident and now works desperately to pay her younger sister's tuition. He abducts and imprisons the adult woman, using her devotion to her sister to force her into sexual slavery.