JUQ-725 Five months into marriage, I got my wife's younger sister pregnant before my wife… Sandayuki Fumi's

It's about time we had a kid... Life has stabilized, and every night my wife and I have been trying to make a baby. One day, my wife's sister, Fumino, was going to stay at our house for five days. Thinking she might be bothered... we continued with our marital duties, but it seems our voices leaked out, as Fumino looked like she couldn't sleep. After that, we started paying attention to each other, and we began having a relationship behind my wife's back. The frequency increased, and all the sperm meant for making a baby with my wife was used on her sister, Fumino.