The Usagi siblings lost their parents at a young age. The older sister, Aika, continued to work hard, graduated from junior college, and became an office lady. On the other hand, the younger brother, Masakazu, liked to play around and didn't study much, but Aika Ke'ai Masakazu, her only family member. One day, Aika gets a call from a man named Kudo on her cell phone. He says, "Your younger brother has damaged the boss of our gang." To settle the score, Aika is kidnapped by Kudo and his men and is subjected to the utmost humiliation...