Adult PC Game: Nanase Mother and Daughter Affair Ver.1.0 by SORAUE Archive

A typical life in a certain town. A daughter, Satomi, is a member of the swimming club and has a clear-cut personality.
The mother, Yuko, has raised Satomi on her own and has a strict personality. The Nanase mother and daughter are not wealthy,
but they live happily together. One day, Satomi broke school’s rule prohibiting having relationships, and the school's student
advisor Shimoyama uses his underhanded tactics to demand Satomi's body. But behind the scenes, her mother, Yuko, is also…
Shimoyama's scheme involves everyone around him, and everyone becomes involved in the affair…