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 her skirt as my younger sister, Sakka, dozed defenselessly. Her translucent skin, her slender, soft ankles. The moment my fingertips gently touched her immature body, Sakka flinched. "N-no..." she said in a frightened voice, her moist eyes, and her gestures as she desperately tried to push back with her slender arms further destroyed my rationality. Her fragile strength only fueled my desire, and before I knew it, I was holding down her shoulders. Eventually, trembling slightly, she intertwined her fingers as if clinging to my arm, and sweet sighs began to escape from her slightly parted lips. Her halting reactions were irresistibly endearing, and before I knew it, I was devouring her delicate body over and over again... There was no turning back.