メビウスロイド

The main protagonist of "Mobius Roid" is a young man named Taniyama Makoto, who lives alone in a mansion in a quiet district, and dedicates most of his time to one activity: sex. He also has a partner to his sexual escapades, a very "active" young girl named Chie. But another young girl is raped somewhere in the neighborhood, and this changes Makoto's life...

[From Moby Games]