Kusuriyubi no Kyoukasho

Toshio is an eighteen-year-old young man who has attended a special school, and now has quite a bit of free time on his hands. He has been raised by his single father, and has enjoyed a careless life in a wealthy environment. Now, his thoughts are directed at his pretty ex-schoolmates. Not everything is as simple as it may seem - Toshio has to plan his moves carefully, otherwise he might fail in his amorous endeavors.

[From Moby Games]