My friend's sister is always dressed sexy. Whenever I go to her house to play, she always shows me her defenseless chest and panties. I can't help but notice my friend's sister, and I end up staring at her body. One day, I accidentally witnessed my friend's sister masturbating. As I couldn't help but stare at her, my friend's sister teased me with her sexy gaze! And that night, when my sister made sure that her brother was asleep...!?