Tsuma no imôto: Abunai chôhatsu

Original title: 妻の妹 あぶない挑発

Machiko left her well-off family to work as a nurse in Tokyo. She hadn't returned home in years, having married her husband, Tokuo, despite her father's objections. Then, upon receiving news of her teacher's death, Machiko suddenly decides to return home alone. Then, her younger sister, Fumiko, comes to visit her at the house where Tokuo was left behind...