Never tell your wife that you got your mother-in-law pregnant. (Tomoda Maki JUY-766)

Because her father-in-law injured his foot, they went on a hot spring trip to recuperate. The father-in-law's desire to see his grandson put immense pressure on the couple, and to make matters worse, the wife was on her period… Then, seeing her mother-in-law's stunning figure in a yukata, it was impossible to suppress one's rationality…