Figure ~Ubawareta Houkago~

An oligarch named Takanashi has built a prestigious girl's high school, known as the Hanatsuki High. Mishima, a young man who has recently graduated high school, is approached by Isao, representative of the Hanatsuki High and his former schoolmate, with a part-time teaching job offer. Despite his dislike to certain school policies Mishima agrees - first, because he is broke, and second, because the perspective to teach the pretty daughters of the wealthiest people in Japan doesn't seem all that unpleasant...

[From Moby Games]