Woo Seul-Ki grew up in an orphanage out in a province. She moves to Seoul and enrolls in Chaehwa High School, which is a school for the top 1% students in South Korea. Woo Seul-Ki doesn't get along with the other students. A student named Yoo Je-Yi approaches her and they become friends.

Yoo Je-Yi is the most powerful student in the school. She has a high IQ, comes from a wealthy family background, and is attractive physically. She has lived as the envy of other people since she was born and she is aware of her superiority. She is also cunning enough to know how to take advantage of her position. She shows special interest in transfer student Woo Seul-Ki. They soon develop a dangerous relationship between friendship and obsession.