Story of Childhood friends who grew up together as sisters at the orphanage .

Ji Won and Chae Won promised to always be there for each others but fate decided otherwise .

20 years later :

Moon Chae Won : 27

She is the CEO of YB Group .

She lost her adoptive mother at 15 which led her to become cold and arrogant.

She lived all these years with her father who was severe and harsh with her .

She intimidates men so she has always been unable to have a relationship the only person she is close to and she trust is Choi Seung Hyun .

Kim Ji Won : 27

Brilliant Architect .

She lives with her hysteric mother who is obbssed about marrying her off .

She is the only family she has after loosing her father .

She barely has any friends because she was always busy studying and working .

Joo Won : 32

Ji Won's cousin .

Surgeon at Seoul National University Hospital .

He has an easygoing personallity but changes girls just like he changes his underwear .

He is known by nurses as the Korean Mc Dreamy .

Kim Woo Bin : 32

Runs a restaurant in Gangnam just to pass time .

He likes to tease people around him .

Doesn't really care about what people say , he just lives the way he wants to .

Choi Seung Hyun : 30

Chae Won's best and only friend .

Son of Chae Won's father associate .

He is a playboy who doesn't love anybody besides Chae Won .