らぶらぶボイン 妹の巨乳

Our protagonist, Umino Kousuke, is a third-year student at Shunpu Academy. His father is on a business trip overseas, and his mother has been staying with his father since April, so he currently lives with his step-sister, Kotomi. After three months, he's gotten used to living alone with her, but his mother soon will return.

Kotomi is petite, 155cm tall, but she has a pretty big bust...no, huge breasts. What's more, she seems to be madly in love with the protagonist.

The "accident" he had hoped for didn't happen, but that doesn't mean Kousuke dislikes Kotomi. But he's the older brother. Kotomi is the younger sister. He's a contrary character who can't be honest with himself.