Lee min - ho is the only son of a humble middle-class couple. Song hye - kyo is the daughter of a strict and rich couple. Both of them study in a residential college located at Shanghai.
They soon fall for each other but question their relationship, whether it's attraction or love. Song hye - kyo is taken away from the college after a picture of them gets published in the newspaper. Lee min - ho is asked to bring his father lest he should not write exams. He goes home and tells his parents a completely different story. While his parents keep thinking that he is studying for his exam, he is busy daydreaming about Song hye - kyo and looking for her. At last, he brings his father to the college, not to write the exam but to see Song hye - kyo. His father is clueless about what is happening and still believes Lee min - ho.
Lee min - ho meets Song hye - kyo and her parents.Song hye - kyo 's parents arrange another marriage for her. Lee min - ho's father learns of his behaviour from his friend. Though disappointed, he believes that children should be dealt with love and not fear. While leaving on a train, Lee min - ho's father dies in an accident. On the same day, Song hye - kyo runs away from her house to live with Lee min - ho , but Lee min - ho doesn't show up because of his father's death. Lee min - ho thinks that Song hye - kyo is with her father and her father thinks that she is with Lee min - ho. Four years later, they both miss each other. Lee min - ho and Song hye - kyo's father meet at a railroad station. Lee min - ho gets to know that Song hye - kyo was not with her father and Song hye - kyo's father that she is not with Lee min - ho. Lee min - ho's mother reaches and tells Lee min - ho that she had Song hye - kyo with one of his lecturers who helped him realize the meaning of life. She kept them away from each other so they realize what life means and also that patience comes from true love only. Now that they are mature enough, none can stop them. Song hye - kyo and Lee min - ho reunite.
After few Days later , Lee min - ho's mother said that Song hye - kyo is your cousin to Lee min - ho . Lee min - ho felt so happy and shares with the Song hye - kyo.
One Day Lee min - ho and his friend Hyun bin decided to join in engineering college located at Shanghai.
Lee min - ho is always top-ranked in his college and Hyun bin poor in studies.
Hyun bin, the grandson of a wealthy song joong -ki, is a spoiled arrogant youngster. He attends lavish parties and spends money recklessly. Hyun bin also breakups with Bae suzy.when she exposes his cheating in an exam. On Hyun bin's birthday, his dying grandfather's will with several conditions is presented to him. It states that Hyun bin would inherit the entire wealth conditions.
Hyun bin struggles to adapt to simple life, he passes the supplementary exams with the help of Bae suzy. who scribes for him because his hands are wounded.
Three months after he joins the college, another condition is revealed that he needs to be elected as the student union president of the college and he must not have a fight with anyone during his time there. Hyun Bin begins to adapt to the conditions and changes his lavish lifestyle. Slowly, he realises the value of life and human beings.
Song hye - kyo, Lee min - ho cousin comes to Lee min - ho's house to continue her studies. Song hye - kyo also joined in same engineering college located at Shanghai. Song hye - kyo takes her first exam and walks out crying as she doesn't understand English, Lee min - ho helps her, and she gets the first rank and Lee min - ho gets second. Lee min - ho is hurt by this as he usually gets first rank, and he plans to sabotage her studies, Song hye - kyo does the same. But to their surprise Kim soo-hyn stands first this time. Meanwhile, Song hye - kyo's father brings her a marriage proposal, but she doesn't want to marry him. Lee min - ho and Song hye - kyo compromise by agreeing to help each other.
Lee min - ho helps her in getting the proposal canceled and Song hye - kyo distracts Kim soo-hyn from studies for the sake of Lee min - ho, but Lee min - ho gets attracted to her. The couple start studying together and Song hye - kyo distracts Kim soo-hyn. Lee min - ho gets first rank and is awarded a building from his principal, at the housewarming party, Song hye - kyo says Kim soo-hyn is great as he studied well even though Song hye - kyo distracted him. Lee min - ho is hurt by this statement because he doesn't want Song hye - kyo to think anyone is better than him, his ego is also hurt and the couple chooses to separate.
After three years, they meet again in the hospital because their grandmother suddenly falls ill. While trying to find out how Lee min - ho is doing, Song hye - kyo realizes he hasn't changed at all. Both argue a lot until their parents try to get them married. Surprisingly, Lee min - ho mentions that he has a girlfriend named that he perk shin-hye hopes to marry. While introducing her to his family, Song hye - kyo notices that perk shin-hye is much more than she is. To get back at Lee min - ho, she agrees to marry Kim soo-hyn , Kim soo-hyn turns out to be the head of a company that makes more than Lee min - ho 's company. Lee min - ho, angry that Kim soo-hyn is greater than he is, puts his company in risk in hopes that he can surpass Kim soo-hyn's company. Unfortunately, his partner cheats him, and Lee min - ho is on the verge of losing his company. Song hye - kyo, now his project manager, toils to rescue him. They make an excellent team and Lee min - ho's company is saved.
Lee min - ho is given party to whole team .In an after party, Lee min - ho credits Song hye - kyo for his success. She again unknowingly hurts Lee min - ho's ego. This time, Lee min - ho confesses that he felt the need to be great in Song hye - kyo's eyes because he loved her. After that Song hye - kyo shares her feelings, But Lee min - ho refuses to believe her. After the interference of their grandfather, they are united .