Looking for hentai

So the setting is classic highschool. The mc has some sort of birthmark on his butt and was harassed as little boy by two girls. Those girls are now teachers at his highschool, one being homeroom and one at the infirmary. Homeroom teachers recognizes him, action starts but the infirmary hesitates to join in. Of course she does later and i think there are more in the harem later.

And i don't mean the manga with the tattoo ass mark