Koukou Kyoushi - Sei Erika Jogakuin Hen

The game has a rather simple premise: the protagonist is a young man who is looking forward to his first day on a new job, that of a teacher at the prestigious St. Erika Girls' High School. Naturally, he won't be busy with teaching alone; the goal is to get acquainted with the various female characters that populate the school, including the nurse and many of the students.

[From Moby Games]