Kei's wife's parents are looking forward to meeting their grandchild. On a trip to the hot springs, Kei's father-in-law asked him to refrain from ejaculating and to try to store sperm for that day. Trying to control himself for a month, Kei could hardly bear it anymore. Upon arrival, he immediately asked his wife for sex, but she refused, wanting to soak in the hot springs first. Disappointed, Kei mistakenly entered the women's bath and caught a glimpse of his mother-in-law's seductive body. From then on, his mother-in-law's image kept appearing in Kei's mind. Back in the room, even though his wife agreed to have sex, he could only think of his mother-in-law. That night, he continued to sneak into the women's bath to peep at his mother-in-law. But this time, Kei lost control due to his intense arousal. He rushed in, forcefully took his mother-in-law and impregnated her. Upon regaining consciousness, he apologized and quickly left. After a long time without sex, being taken to climax repeatedly by her young and vigorous son-in-law made it unforgettable for his mother-in-law. That night, they coincidentally met again. Without saying much, the son-in-law and mother-in-law immediately engaged in passionate sexual pleasure. After some time, the mother-in-law became pregnant. Despite the surprise, his wife and her parents never suspected the child in her womb...