Based on the H-game by Amalgame.

Certain subjects being taught these days at college aren't always on the curriculum...

Sex education is one of them! Here at our all-girls school, one male teacher takes it upon himself to best educate students in the ways of carnal knowledge. Using (and abusing) his authority, he lures the hottest students into his lair and has his sleazy way with them! In the the end, these girls will learn some lessons they'll never forget.

At another college, a glowing phallus-shaped artifact possesses magical powers that turn innocent girls into raging sex maniacs. When a teacher is seduced by a student, he soon finds himself endowed with a power that the girls cannot resist...

(Source: AniDB)