My ordinary life was suddenly disrupted when my wild, aggressive older brother and his woman, Nao, showed up unannounced at my home. Even while staying as guests, they treated my house like their own, freely indulging in sex whenever they pleased. Then one day, my brother vanished without a trace, leaving me alone with Nao. Five months passed like this—sharing daily chores, going shopping together, living side by side. Gradually, I found myself drawn to her. She was someone I should never have touched, but I couldn't resist being captivated by her warmth and kindness.