My sister Haru is the most beautiful girl at school—slender, perfectly proportioned, and stunningly attractive. I, on the other hand, am a timid virgin, her complete opposite. One day, while I was masturbating as usual, Haru caught me. I thought it was the end, but instead, she suddenly started sucking my cock. Then, as if a switch had flipped, she aggressively started seducing me for sex.