Jang, Young-Sun

She is an attractive young woman who is daughter of a rich man. She pretends to be Han-Ah's friend, but in truth she envies her and doesn't want her to be happy. It's been told that she is the daughter of a mistress. Also, she used to date Mi-Yoo before moving, but she broke up with him because he suffocated her. She tries a lot of different and persistent methods to break up Han-Ah and Yoo-Min, but all her extra efforts were in vain. She decides to use Mi-Yoo, and it results in Mi Yoo catching Han-Ah together. After they separate, she no longer talks to Mi-Yoo, and he becomes aware that she was only using him. He tells her that she can't date Yoo-Min. She ignores him and goes to visit Yoo-Min at the hospital. Then Mi-Yoo calls her telling her to forgive him for what he is going to do. She discovers, later by a phone call, that he kidnapped Han-Ah, and he tells her that Han-Ah is the only one she has opened her heart to. She realizes is true. After Yoo-Min saves Han-Ah, she visits Mi-Yoo at the hospital, and he tells her that she hasn't changed. She is still the same spoiled, lonely girl from kindergarten. She meets Han-Ah outside and Han-Ah hugs her. Then she tells her that she was envious of her happiness and of her scent. Han-Ah tells her the secret Mi-Yoo told her while the kidnapping : "Let me tell you something about your future, You'll... be happy". From Wikipedia