You are Woo Seul-gi. An orphan girl. You don't have any friends at the orphanage, all you do is study all day, you are the best student at your school, but you don't have any friends there either.

One day, mysteriously, a rich family from Seoul adopts you. They change schools and take you to a big mansion. When you are there having dinner with everyone. Your adoptive parents and your sister, you notice that she can't stop looking at you. Her gaze is strange, she looks at you with desire and something else... with, obsession?