The second Bangai-hen (a side story) in the Tenshitachi no Gogo series is set in the same environment and features recurrent characters from "Tenshi-tachi no Gogo 3 Ribbon". The protagonist is a high-school student, who also happens to be the brother of Haru Okamoto, the main love interest in "Ribbon". Like in most other games in this series, the story revolves around the main character's effort to have sex with every female character, including school mates and colleagues in part-time jobs.

[From Moby Games]