While his wife was pregnant and visiting her parents' home, a busty older sister had sex with him, her erect nipples making her feel the immoral act. (Yoshii Miki, JYMA-073)

We'd been married for five years. After my wife became pregnant, she said she wanted to give birth at her parents' home, so I started living alone. My wife's sister came to help with housework. Although I knew it wasn't appropriate, as a single person, I still kept an eye on her. Being alone with her at home made me uneasy. That's when I saw her masturbating; our eyes met, and from that moment on, we began our forbidden acts…