Kim Hyoyeon (25) became a gangster and adopted the nickname "Warm Killer."  She is seen as popluar, and famous of being rude, , insensitive and a very cold and distant being young lady. But still, Everyone loves her. She is in fact lonely, sweet, understanding, yet warm and kind lady.  She is the eldest daughter of Mr Kim. The owner of the biggest company in seoul. As she turn 16, Everything has changed. She spent her entire life in the gangster world and only knows how to be tough. Until she meets the arrogant hallyu star neighbor, Park Yoochun. At first, she is irritated by his arrogant and being smug. She secretly begins to open her heart to him. But still acts very cold towards him. She soon become Yoochun's secret Protector. Since she is a part a gang, she is no allowed or she PROHIBITED to fall in love or like someone.
Park Yoochun (29) is a famous top Hallyu star.  He is every women's type. He seen as a self-centered, naughty, ambitious, immature and irritating young man. Beside of being celebrity he is also a businessman. He attends the same school and same condominium unit floor as Hyoyeon,  But he is infact, a kindhearted, innocent, honest person. Who develops feelings to his next neighbor door Hyoyeon and tries to make her fall for him.

Kim Taeyeon (27) - Hyoyeon's childhood bestfriend. Famous of being rude and too.  (She owns the biggest club in seoul)

Jung Jessica (25) - A Hallyu star and famous actress and a secret close friend of her. Who is there to protect this friend.

Hwang Tiffany (26) - A doctor, Who got divorce 4yrs ago. Hyoyeon's personal doctor. (Owns the popluar hospital in L.A)

Kwon Yuri (22) - Genius and innocent, She betrayed hyoyeon for this love to Won Bin (Owns the famous museum and hotels) 

Song Mino (23) - Came from the riches family, Jessica's die hard fan as Jessica soon develops feelings towards him.

Nikchun (27) - A doctor, Tiffany's ex husband. Sucessfull businessman.

Kim Jinwoon (24) - Taeyeon's understanding boyfriend

Kim Jaejoong (28) - Hyoyeon's richest suitor, CEO of SNC. Yoochun's rival in showbiz industry.

Kim Hyun Joong (28) - Hyoyeon's heartrob suitor, He likes hyoyeon since High school.

Kim Woon Bin (24) - Hyoyeon's childhood friend, Who has unrequited love for her. But in the end, He becomes hyoyeon's supporting friend.

Kim Jong-in (Kai) (18) - Hyoyeon's protective brother who have the same personality as her.

Hyori & Bom (32) - Yoochun's elder sister.