MIAA-384 Doing It With My Girlfriend's Younger Sister Until Morning As We Both Sheltered From The Rain - Rin Kira

I was thinking of marrying the girl I was living with. She has a younger sister who is a little older. Her name is Rin... She's friendly, she's already called me Onii-chan, and she talks to me affectionately. One heavy rain day, Rin was soaking wet and evacuated to our house. … A big thunderbolt caused a power outage, and the moment I touched Rin's body as she hugged me, my reasoning was blown away and I just had raw sex. Seeking each other...