During University's Fall holidays I went back home and met my little sister who has been a NEET for over a year...

One day, our parents went on a business trip. I caught my little sister sneakily mailing her worn underwear to strangers... I immediately confronted her and attempted to lecture her.

But her response surprised me...

As her big brother, I have to change her for the better, on behalf of my parents! Using our alone time, I will train my sister and release all her pent up desires and relax her body...

[Translated from DLsite]