Momo and Karin are sisters who grew up in a wealthy family. However, one day their parents suddenly die in an accident, and they are taken in by their uncle. Although they are nervous, they go to their uncle's house, encouraging each other that they will be fine as long as they are there. Their uncle greets them and seems kind, so Momo and Karin fall asleep in relief. However, the next day, Momo and Karin wake up to find themselves naked and handcuffed, and are shocked. Their uncle comes in with a lewd smile on his face, revealing his intense hatred for Momo and Karin's father. He tells them that from today onwards, they will compete in sexual services for their uncle to decide which "daughter" truly loves his uncle, and the loser will be kicked out and without a family.