Gu Jun Pyo is the heir to the Shinhwa company, a very rich well-known company. As a child until a teenager, he doesn't live with his parents but with his sister (noona-Gu Jun Hee). Noona is the only person he listens to and she is the only one who could control him. He is know of the rebelious, flirtatious and spoiled boy. He's the leader of F4. F4 was formed when they were in Kindergarden. A transfer girl named Geum Jan Di, who hates the way that be beat up kids, stood up to him and do all these kicking and yelling at him which caught F4's attention especially Gu Jun Pyo. At the start, Geum Jan Di has feelings for Ji Hoo (F4 member, Gu Jun Pyo's best friend), but as the plot develops, she starts growing stronger feelings for Gu Jun Pyo. Gu Jun Pyo's mom know about this and she use all the power she has to stop the relationship between them. Jan Di, Jun Pyo and Ji Hoo has to go through lots of trouble to get Jan Di. He onced lost his memory due to a car accident that makes him forget who Jan Di is but he still remember who everyone else is. F4 and Noona was curious why he forget who Jan Di is and the doctor said that she is the most important person in his life that he cannot live without that makes him forget who she is. But later, he got his memory back and 4 years later (right after he gets back from study aboard in America) he propose her to be his wife and she accept it.