Yonghwa was raised in North Korea, he’s the son of the head of North. His father is a North Korean while his mother is a South Korean. She died when she gave birth to him. On Yonghwa's 21st birthday his father presented Yonghwa his very 1st A-list mission. It was to send Yonghwa to spy on the South’s daughter by becoming her personal "undercover" body guard. His father holds a powerful grudge on the South, knowing that she's his weakness. The closer Yonghwa gets to her, the closer his father gets to destroy the head of the South, but will Yonghwa's secret mission succeed.

Shinhye is the daughter of the head of the South. Her best friend is Park Seyoung. She’s a lovely daughter to her father and mother. Shinhye's father adored her to the point of harming whoever dares to harm her. Even her boyfriend Lee Min Ho, they been together for 3 months. But what she doesn’t know is that he’s a player. He’s been messing around with other girls during their 3 months together.

Lee Min Ho is Shinhye's boyfriend for the past 3 months. He only dated her to get a good reputation, even though he truely kind of loves her. But you know what they say, guys like him can't stay with only one girl the whole time. He works under the head of the South, he's the leader of the secretary team of the head of South's building. 

Park Seyoung went to the same school with Shinhye that was how they became best friend until now. Other people sometimes mistake her as Shinhye's sister because they have the same last name also they're always together like glue. (Very few parts of her though.)

Lee Joon is also from the North, Yonghwa's best friend. He's Yonghwa's assistant, during his time pretending to be a personal body guard. Whenever Yonghwa gets into trouble or gets injured, it's his job to protect him. 

Yoon Doojoon, is the head of the South's most trustforte personal body guard. His role is to protect him no matter what, also to look out for his daughter. (Very few parts of him though.)