As the eldest son of the Tanaka family, I moved to Tokyo to attend college, living together with my younger sister, also a university student, away from our hometown. One day, while my sister was out, I was masturbating with a porn magazine for the first time in a while—when suddenly, she returned home. She caught me in the act, and though I panicked and tried to hide it, it was already too late. Seeing my reaction, my sister said, "Onii-chan... if you're going to jerk off to porn, why not use my body instead?" Then she stripped naked, revealing her surprisingly developed breasts and ass—far beyond what I'd ever imagined since childhood. Helplessly, I became fully erect. When I touched her sensitive nipples for the first time, her body twitched in response, driving me even wilder. She showed me her soaked panties dripping with arousal, and when I slid a finger inside, she instantly climaxed. At that moment, she confessed, "Onii-chan... I love you so much... let's get married..." reaching out with her tongue to give me a passionate French kiss. After intense blowjob and nipple sucking, she mounted me cowgirl-style, taking my cock bareback. Drunk with pleasure, she writhed her hips wildly, climaxing again and again. Finally, she begged, "I want to get pregnant with your baby... come inside me!" clinging tightly as I tried to pull out, forcing me to creampie her deeply.