My little sister who comes to my room almost every day and makes fun of me as a virgin. Today, she showed off her panties in front of me and teased me for pretending to masturbate... I couldn't stand it anymore, so I decided to secretly do something erotic while my sister was sleeping. Even if I take off my clothes and touch my nipples, I won't find out, so my sister gets up when I'm playing with my pussy through my pants...! However, the unexpected words "I want to do it too" came from my sister's mouth instead of yelling. That's right, this and that were all according to my sister's calculations...