The overly serious girl, Hoshizora-chan, couldn't keep up with her classmates' discussions about sex and was secretly troubled. One day, she mustered the courage to visit her PE teacher's home on a day off to learn about sex from him. However, that teacher was a pure lecher who went to brothels every week. Initially, he tried to get rid of Hoshizora-chan, who had come to his house because he was going to a brothel, but then he took advantage of her troubles and began to manipulate her developing body. The serious Hoshizora-chan also gradually came under the teacher's control, both physically and mentally…
