Take Care of The Young Lady, also called My Fair Lady. I'm currently watching it right now. Yoon Eun Hye and Yoon Sang Hyun are the lead characters. I like both of them but I have some problem with their chemistry since Yoon Hye seems like very young compared to Sang Hyun. No offense to Sang Hyun fans. I'm just starting so the chemistry may develop later on. Anyway, this is the exact drama based on your description. She is really mean like male version of Gu Jun Pyo but meaner. I think her character will go back to good in the end since she was very nice before experiencing a major heartbreak.
You're All Surrounded. The lead girl, Go Ah Ra was very mean when she was young. She was like the annoying and mean female alpha in high school who dreams to be a celebrity someday. Lee Seung Gi when he was young was very cute and kind middleschooler. Then when they grew up, role reversal. She was nice and he went cold. It's a nice drama. Crime solving with a touch of romance.
Secret Garden. My ultimate fave Korean Drama. Ha Ji Won's character was a little mean to Hyun Bin's character. Not so mean but mean because she kept rejecting him to the point that he was always hurt. Its a great drama to watch because of the oozing chemistry of both leads.
