Onna Kyoushi

This explicit anime takes place at an unusual school in which sex between students and, above all, with teachers, seems to be the norm rather than the exception. This first volume of the aptly named HOT JUICY TEACHER series focuses on Yuichiro, a formerly good-natured student who has turned twisted since being falsely accused of rape at a previous school. At his new school, he encounters a group of perverted, abusive bullies, some of their victims, and any number of extremely attractive and libidinous young instructors. Excellent character design and quality animation set this apart from the genre's many similar titles.
(Source: AniDB)