I somehow transmigrated into a 19+ reverse-harem novel. The problem is, I became the older sister of the minor villain... And my damned father went and kidnapped the female protagonist's older brother. Does that mean my only future is to be ruined and exacted vengeance upon by the heroine's family? Ah, it's really hard to avoid death flags. "I'm interested in this new toy myself." Brother, since things have turned out this way, I will protect you. So you must definitely repay this favor later, okay?