[MKON-025] Really Gomen... I was forced to promise by the friend of the class that I'll let my sister's lick Sachiko

I made a promise to my friend to lick my sister's. When I told my sister about it, she said, "... It's good. To be honest, I thought I would be refused, and I was shocked by my sister, who had no idea of chastity. Because it's not good to let a stranger lick his tits! I didn't have any sign son of my boyfriend until now, but I wonder if he was actually a. That's how the class came to our house. From now on, my sister is going to be licked by her.