My Sister Let Down her Defenses on me 2

I always thought she was still just a kid, but when did she grow into such a woman's body... One day, I found myself lusting after my little sister's body. When I got home, my sister 'Uta' was home alone. She said our parents had gone out. She said she was sleepy and went to her room, saying 'I'm going to take a nap.' As I passed by her room, my sister was masturbating with a vibrator!! Heavy breathing... Then, as she began to breathe deeply in sleep, I caught sight of her wet, hairless p*ssy... I couldn't help but feel forbidden desire for my defenseless sister's body—a wrong 4-part story!!