Violet Plan ~Kansei no Reijo~

Satomi works as a lecturer in a law school. She has a girlfriend among the students. Kazuki offers himself as a partner to Satomi, but is rejected, and his pride suffers greatly. Kazuki lays out numerous traps to insult and shame Satomi. After success, he delivers the same scheme for other girls. That plan gets a name "Violet plan".

[From vndbreview]