Mako Oda, 36, is a busty married woman. Her huge breasts are visible even through her clothes, and the caretaker of the apartment building she lives in is captivated by them. One day, the gambling-loving caretaker is struggling to collect debts, so he kidnaps Mako, who lives in the same apartment building, and offers her up to a loan shark in exchange for the debt. The loan shark immediately holds a busty rape event, collects a large amount of participation fees from the bukkake-loving salarymen, and makes the reluctant Mako go crazy in a group rape, making her the victim of a group bukkake. He then trains her as a sex slave.