Forty-year-old single mother Rika Fujishita begins working as a temporary employee to support her son's overseas studies. One day, while working late, her company's president offers her a full-time position—but forcefully takes her against her will. That night, when her son comes to pick her up, he opens the office door and hears his mother's moans. Shocked and confused, he confronts her, but gradually becomes drawn into a forbidden relationship. Awakening the woman within her, Rika develops an intense sexual desire, undergoing a dramatic transformation. Soon, the taboo bond between mother and son deepens beyond return.