Mizugi no Shimobe-kun ~Shojo ni Osowareru Umi no Ie~ by Lilith Soft - Adult Sex Game

Kouhei is the professor at the school of students Kaede, Kyoka and Yuki! There's a line these four can't cross. But Kaede, Kyoka and Yuki have broken through the forbidden barrier.

The girls seduce him with domination so he'll agree to take their virginity. Become Kouhei, and get it on with deliciously naughty teens...