Adult PC Game: Helen’s NTR Summer School Training - Version 1.03 by Gyakushuu no chii ush (Eng) Archive

As Ichimotsu Saoya, a middle-aged physical education teacher, you witness your masturbatory crush, the recent international student Helen Anderson, having sex with a student from another class, Ninomiya.
Now, you must plot your revenge by tricking (or rather, blackmailing) Helen into extra summer school lessons during her summer vacation with a sexual consent contract.

Helen’s NTR Summer School Training - Version 1.03 by Gyakushuu no chii ush (Eng) Gameplay Preview