After graduating from college and moving to Tokyo for work, I returned home for a three-day holiday to visit my family in the countryside. The moment I arrived, I reunited with my sister, who had quit her job and was happily living as a freeter. Dressed in an unflattering tracksuit, she looked completely different from the person I once knew. Captivated by her carefree appearance and secretly voluptuous figure, I became aroused and ultimately couldn't resist assaulting her. As I groped her large breasts and enjoyed her reactions, her long-dormant desires awakened, and she began aggressively demanding more sex, one round after another. Our relationship rapidly deepened, transforming the bond between us into something entirely new.