Takashi-kun, you must control yourself until the hot spring trip next month,” my father-in-law said to me. The thing is, my father-in-law has a backache, and our family hasn't traveled together for a long time, so on the upcoming break next month, the whole family will go to the hot spring. My father-in-law really wants a grandchild. It is said that hot springs are very good for 'making babies,' so he asked me to control myself, accumulate sperm for a whole month! And the day has come, because I have endured for a month, I have been craving it a lot! But no matter how much I demand, my wife still refuses! Unable to sleep, I walked around to breathe fresh air and met my mother-in-law. Despite her age, my mother-in-law is still extremely beautiful. When I saw her entering the bathroom, I couldn't help but follow her. Observing her voluptuous and seductive body, combined with the pent-up arousal from restraining myself for a month, I couldn't control myself anymore! I rushed to possess her body and released all the accumulated sperm deep inside her! After regaining my composure, I immediately apologized to her and left. But the arousal persisted, so I went to my mother-in-law's room again. Afraid my father-in-law would wake up, my mother-in-law pulled me into the bathroom and took the initiative to have sex with me! It turns out that because my father-in-law has a backache, he hasn't had sex with my mother for a long time, and her arousal has been building up even longer than mine! After understanding each other, we secretly continued to make love throughout the trip. A few months later, my mother called my wife and me over and announced that she was pregnant. My wife and father-in-law were very happy, but only my mother-in-law and I knew that the baby in her womb is whose...