While delivering a student's dry cleaning, Geum Jan Di saves the life of a student at the most prestigious school in South Korea. Her actions soon became public and exposed the bullying within the school. To silence the public's attention, Jan Di is offered a swimming scholarship to Shinhwa which she declines but her family forces her to attend.
During her first day at Shinhwa, Jan Di learns of the famous F4 and of the other students' adoration and fixation with the boys in the group. Gu Jun Pyo, Yoon Ji Hoo, So Yi Jung, and Song Woo Bin are the richest and most powerful kids within Shinhwa and South Korea. Subsequently, they use their power to terrorize weaker students or those they do not like. Jan Di, instead of being impressed, becomes enraged and fantasizes about confronting Gu Jun Pyo, the leader and initiator of many of the bullying acts. She gains courage to confront him when a friend , named Oh Min Ji , accidentally spills ice cream on his shoes and he demands the girl to lick it off. Jan Di defends her friend and attempts to reason with Jun Pyo's tyrannical demand. When he refuses to relent, Jan Di turns violent, knocking Jun Pyo to the ground. Engaged by this, Gu Jun Pyo declares war on Jan Di and encourages the other students to bully her. Jan Di, however, is resistant, refusing to apologize to Gu Jun Pyo, and stands by her decision to fight him.
Ironically, Gu Jun Pyo, having never been stood up to, begins to develop feelings for her. He tries unsuccessfully to woo her as she slowly begins to spend more time with Jun Pyo and his friends. Jan Di teaches Jun Pyo that money cannot buy everything and in order to have real friends, he himself must be real or use his heart, but Gu Jun Pyo still does not understand why someone like Jan Di should dislike him. As the story progresses, Jun Pyo falls deeper in love with Jan Di and she learns how to open herself to his love as well.
As love begins to blossom, Jun Pyo's mother discovers them and deems it unsuitable. She does everything in her power to keep the two apart, even arranging a marriage for Jun Pyo. The other F4 members and Jan Di's best friend, Chu GaEul try to make their relationship better. So Yi Jung and Song Woo Bin came up with a few plans but it fails. They left with no choice but to use the last plan. The plan is So Yi Jung have to make a fake date with Ga Eul. At first their plan is successful but because of Jun Pyo's mother the relationship between them is getting further again.
After the fake date, Ga Eul finds her self falling in love with So Yi Jung. So Yi Jung feels the same way, but he won't admit that he is falling for her. Other factors keep arising as another member of the group falls in love with Jan Di (which was Yoon Ji Hoo) and in a twist of fate, Jun Pyo loses his memory. A girl named Jang Yu Mi which was on the same hospital where Jun Pyo was confined, takes advantage on him to make him fall in love with her. Geum Jan Di never gives up for Jun Pyo to rember his love for her, she falls in the swimming pool letting Jun Pyo reminise his love for her. On Jan Di's graduation, Jun Pyo proposes to her on the cable car at the NamSan Tower where their first date was held. Gu Jun Pyo told Jan Di that he needs to study abroad to fix problems regarding Shinhwa. Jun Pyo asks Jan Di to accompany him as his wife but Jan Di refuses because she has also plans for her future becoming a doctor. The two agreed but Jan Di told Jun Pyo that she will be waiting for 4 years in one condition--if Jun Pyo comes back as a handsome and charming man.
The story ends with f4 four years later with each cast revealing happenings on their current life--Yi Jeong coming back form Sweden for helding his art exhibit, Ji Hoo who just opened his Grandpa's clinic, Ga Eul who was teaching the art of pottery to preschoolers and Woo Bin becoming a happy man but his career was never mentioned in the story. Lastly, Geum Jan Di went to the beach to see Jun Pyo, Jun Pyo then scolds her for being late in just 5 minutes. He then proposes to Jan Di but the answer was still a question among viewers because when Jan Di was about to answer--Ji Hoo, Yi Jung and Woo Bin arrives saying that they object to the proposal because Jun Pyo and Jan Di didn't ask for their permission first.
CAST
* Koo Hye Sun: Geum Jan Di is the first girl to stand up to the leader of F4 Jun Pyo, and the first girl to earn the infamous Red Card. Through this, a chain of events ultimately leads to her falling in love with Ji Hoo and then Jun Pyo, as well as F4 becoming her closest friends.
* Lee Min Ho: Gu Jun Pyo is the hot-headed leader of F4 and the heir of the Shinhwa Corp Group. He's the youngest billionaire of Shinhwa Corp. While still in high school, he meets Jan Di and is stunned by her act of defiance. Though at first determined to make her life miserable, he falls in love with her.
* Kim Hyun Joong: Yoon Ji Hoo is a calm and soft-spoken boy who likes to play the violin, piano, and guitar and conduct an orchestra. He serves as one of Jun Pyo's best friends and main rival for Jan Di's heart.
* Kim Bum: So Yi Jung is F4's perennial playboy. He is from a family of well-known artists and is a reputable potter himself, making his first debut at the age of sixteen. His family owns a famous art gallery that exhibits national treasures.
* Kim Joon: Song Woo Bin is from a family that runs an underworld organization, hinted to be the mafia. He is often seen betting with Yi Jung over various matters. He is one of the two F4 playboys.
* Kim So Eun: Chu Ga Eul is Jan Di's best friend since kindergarten. She and Yi Jung work together and even go on a fake date in order to bring Jan Di and Jun Pyo back together. Eventually an attraction evolves between them throughout the series.She falls in love with So Yi Jung...
Additional Cast
* Lee Shi Yeong: Oh Min Ji is Jan Di's first friend when she transfers to Shinhwa High, secretly manipulating her to destroy Jun Pyo.
* Han Chae Young: Min Seo Hyun is Ji Hoo's first love and a famous Korean model.
* Jung Eui Chul: Lee Min Ha/Lee Ji Ha are two characters played by the same actor, first as the student that is saved by Jan Di, and later as his vengeful twin brother.
* Lee Min Jeong: Ha Jae Kyung is Jun Pyo's fiancee in the latter part of the series who makes her first appearance when she runs into Jan Di in Macau.
* Im Joo Hwan: So II Hyun is Yi Jung's estranged older brother who threw away his family name in order to live a normal life. He carries a heavy burden for abandoning Yi Jung.
* Park Soo Jin: Cha Eun Jae is Yi Jung's first love. She is a teacher at a pottery class where Ga Eul goes, causing her and Yi Jung to cross paths after 3 years apart.
* Kim Min Ji: Jang Yu Mi is a girl at the same hospital where Jun Pyo was confined who takes advantage of his amnesia.
Geum Family:
* Ahn Suk Hwan: Geum II Bong
* Im Ye Jin: Na Gong Ju
* Park Ji Bin: Geum Kang San
Gu Family:
* Lee Hye Yeong: Kang Hee Soo
* Kim Hyun Joo: Gu Jun Hee
* Jung Ho Bin: Jeong Seongrok
Mean Trio (Jin Sun Mi):
* Gook Ji Yun: Choi Jin Hee, known as Ginger
* Jang Ja Yun†: Park Sun Ja, known as Sunny
* Min Yeong Won: Lee Mi Suk, known as Miranda
