Tenshi-tachi no Gogo III Ribbon

The third game in the Tenshitachi no Gogo series is not connected to its predecessors story-wise. In this installment, the player assumes the role of a male teacher in a high school. Many pretty female students (and pretty female teachers) surround the hero, but he only has one girl in mind: Haru Okamoto, whom he calls "his angel". In order to win her love, the hero will have to know her better - which also means knowing the secrets of students and teachers alike...

[From Moby Games]