Nanako married Satoshi, a university professor, as a means to cover her bedridden father's hospital bills and her family's living expenses. However, her stepson, Kazuya, discovers the financial arrangement between his parents and, realizing the situation, forcibly assaults Nanako, raping her against her will. Though they share no blood relation, the fact that she has been violated by her stepson plunges Nanako into despair. While she could have reported the crime or left the house, she feels trapped with no escape. Each step of this unfolding tragedy strikes deep into the heart.