Five months into their marriage, he got his wife's younger sister pregnant before his wife could... (Satsuki Fumino JUQ-725)

We were almost ready to have a baby... Life had settled down, and I spent every day with my wife. One day, her younger sister, Satsuki Fumino, came to stay for five days. We continued our sex life as a couple, being careful... but it seemed we were making noises, and Satsuki Fumino couldn't sleep. Later, we both realized this, and without my wife's knowledge, we had sex with Satsuki Fumino. Gradually, the frequency increased, and all the semen we ejaculated in our efforts to conceive was used on Satsuki Fumino.