A group of 4 close friends went to a hot spring after a long time without meeting each other. In fact, this trip had another purpose. Ken-chan secretly loves Asami-chan but didn't have a chance to express his feelings to her. He then asked his close friends, who are now a married couple, for help. So they organized this trip so that the two could get closer. Nao and her husband helped Ken-chan achieve his goal. But that night, witnessing Ken-chan having sex aggressively with Asami-chan aroused Nao. She couldn't stop thinking about Ken-chan and when he accidentally entered the women's bath, Nao held him back and used her charm to seduce him, making him ejaculate inside her repeatedly. When she returned, Nao was pregnant, and that pregnancy is very likely to be from Ken-chan...