The overly serious girl, Hoshizora-chan, was struggling to keep up with her classmates' conversations about sex and secretly worried about it. One day, she decided to visit her physical education teacher's home on a holiday to ask for advice about sex. However, the teacher was a genuine lecher who frequented brothels every week. Initially, he intended to get rid of Hoshizora-chan because she interrupted his brothel visit, but then he took advantage of her worries and began to manipulate her developing body. The earnest Hoshizora-chan took the teacher's words to heart and gradually had her mind and body dominated...
