[UNCENSORED-LEAK] SONE-822 I was so horny for my girlfriend's innocent, shy, and immature sister that I secretly had sex with her.

I went to my girlfriend's house for the first time. My eyes were drawn to the delicate thighs peeking out from under the skirt of my defenseless dozing younger sister, Sakka. Her skin was translucent, her ankles slender and soft. The moment my fingertips gently touched her immature body, Sakka flinched. "N-no..." she said in a frightened voice, her eyes watering, and her gestures of desperately trying to push back with her slender arms, further destroying my reason. But her unreliable strength was the opposite...