Yoo Jung repeatedly breaks up with Hak Chan. Each time Hak Chan has changed his habits to be more accommodating. This time he does not know the reason for the break up. Yoon Jae and Joon Hee, the top two students, plan to enter the Air Force Academy. Yoon Jae wants to become a pilot because as a child he hears that Shi Won wants to marry a man in uniform. Joon Hee wants to go where Yoon Jae goes. But Yoon Jae does not make it. He later becomes a judge. Joon Hee appears to also not have made the physical exam for the Air Force Academy.Shi-Won's fan fiction stories reveal her literary skills. She wins a writing contest and gets into Dongguk University. She is happy to enter the same university where Tony An is enrolled at. Eventually she becomes a screen writer. Tae Woong as a teacher encourages students to pursue dreams. He also wants to pursue his real dreams, so he gets ready to resign. His mother had wanted him to become president of Korea.

It is finally the D-Day for the college entrance exams. Afterwards the students make elaborate plans. Seong Jae wants to pick up girls, so he goes to a karaoke bar with Joon Hee. They try to pick up girls, but one girl turns out to be his sister. Hak Chan invites Yoo Jung to his house to watch a videotape he has made for her. She thinks he wants to seduce him into bed, so she honestly tells him she has her period. Yoon Jae wants to meet Shi Won after the exams. So does Tae Woong. Yoon Jae carefully plans to tell Shi Won that he likes her and buys her a dog. Tae Woong wants to take Shi Won out for a drink and also tell her that he likes her. Yoon Jae is shocked to find out his brother's plans. He realizes that the most important thing about D - Day operations is scouting the field, which he did not do thoroughly.

Yoon Jae finally reveals to his classmates that their math teacher was his brother. They are shocked and had no clue because the teacher had been using a false last name. Shi Won's father warns Yoon Jae to meet a sweet woman or he will end up just like him. Shi Won's mother ended up with her husband because of a misunderstanding. But couples end up as fate would have them. Yoon Jae gives the dog to Joon Hee, who gives the dog to a child in the park. But the dog ends up in Shi Won's house as originally planned. Tae Woong starts up an online site where people can find their old classmates and becomes very successful. He asks Shi Won to date him and buys her a phone. Yoon Jae tells Shi Won to stop behaving childishly when she hugs him. He is trying distancing himself from her.

"The reason why I like you is because you're you. Could there be another reason? I wish I knew. Then I could figure out how to stop liking you." People are asked this question and there is no better answer. Sung Jae falls in love with Gak Ha after seeing her dance but tells her too honestly about his reason for liking her. Shi Won thinks Tae Woong likes her because she looks like her older sister. Joon Hee and Yoon Jae ask each other why the other likes Shi Won. Joon Hee confesses that he likes Yoon Jae, but Yoon Jae thinks he is joking in order to avoid the question why he really likes Shi Won. The Golden Disc Music Award is held in Seoul, and there is great tension between the H.O.T. fans and Sechs Kies fans over who will win the grand prize.

Hak Chan keeps avoiding meeting Yoo Jung's friends. Finally he shows up and pays for the bill, which makes Yoo Jung's heart melt. But when Hak Chan does not introduce her to his mother as his girlfriend, Yoo Jung breaks up with him. Shi Won's parents go on a cruise vacation leaving Shi Won alone. On her way back home from working at the convenience store, a man follows her. Afraid, she repeatedly calls Yoon Jae, and Yoon Jae repeatedly calls her. But they do not get connected until she calls his home phone. Yoon Jae dashes to where she is, bleeding with only one slipper. Shi Won realizes that their relationship is not simple friendship, but it is a complicated relationship between a man and a woman.

Shi Won's parents are worried that she will have adjusting difficulties in Seoul, but Shi Won is excited to go to Seoul and has been packing in advance.Yoo Jung is suspicious of Hak Chan and Dan Ji. Hak Chan has been distant. He finally tells her that he is going to Hawaii to study. Yoo Jung tells him that all she wants is that he communicates with her.It is Shi Won's birthday, so there is one last party before everybody parts ways. Shi Won told Yoon Jae the year before that he should tell a guy to buy her a ring for her 18th birthday. This year, she asks Yoon Jae if he has a ring for her. He tells her his feelings and that she is cruel to ask for a ring from him. She asks to be friends, but he tells her he never wants to see her again. Tae Woong gives Shi Won a ring, but she tells him that she needs to talk.

Yoo Jung's father passes away. She realizes that there are no next times. She should have been good to him when he was around. Her friends come to the funeral. Even Hak Chan finally shows up. Shi Won runs into Yoon Jae in a coffee shop. He had avoided seeing her for 6 years. She asks if he has a girlfriend and catches him lying. Shi Won tells him that she likes him. Yoon Jae hesitates to answer, even though he knows that there is never a next time. Meanwhile, Tae Woong has been Daddy Long Legs to Shi Won throughout all this time. He asks her if Shi Won knows how the ending of the story goes, telling her that he wants more. Shi Won does not want more from him. Even 6 years ago, Shi Won told him that she likes somebody else. Yoon Jae overhears Shi Won and Joon Hee talk about both of their crushes on him. He is beyond shocked.

It's what the heart demands. So do what the heart tells you to do. Joon Hee tells Yoon Tae that he should not make his brother the excuse for not being honest about his feelings. People's hearts do not choose who they like. Also he tells him that he should not be bitter towards her for not knowing that Yoon Jae liked him all this time, because some people may not know ever. Joon Hee lies to Yoon Jae about why he needs to move out. Tae Woong is hospitalized to remove his polyp. He meets his surgeon in funny way. She farts and takes her stockings off not knowing he is in the room. He finds out that she will remove his polyp in a most embarrassing way.Shi Won says that if Yoon Jae does not tell her if he likes her, she will kiss him. Yoon Jae kisses her first. Later, Shi Won and Joon Hee talk on the phone afterwards about it. Tae Woong overhears the conversation and is shocked.

Tae Woong asks Yoon Jae to meet a girl. Yoon Jae suspects that it is a blind set his brother is setting him up on. He tells him not to set him up like this again. Tae Woong tells Yoon Jae that he knows about them. Yoon Jae tells him that he gave up Shi Won back in high school for the person he loves the most, his brother. But Tae Woong tells him Yoon Jae that he cannot give up on Shi Won even for his brother. After much anguish, Yoon Jae tells his brother that he will not give up her for his older brother again. Shi Won tells Tae Woong that she has something to say to him. She feels she cannot go on ignoring his advances because he is a dear person to her. Back into the future, Shi Won is having a baby. Both Yoon Jae and Tae Woong come running.

Finally we know who the father is. Tae Woong is dragged to a DBSK concert by his colleagues. He ends up meeting his surgeon again and ends up with her. The two couples talk about who get married first. But Shi Won ends up getting pregnant, so they quickly get married. Tae Woong ends up marrying his surgeon, who becomes the president of the DBSK fan club of Korea.At the reunion, Yoo Jung and Hak Chan talk about their honey moon plans and ask Sung Jae to join them. Yoon Jae asks again who Shi Won would save if Tony An and Yoon Jae were drowning. He realizes that people say that first loves do not last, but that is because the dramatic stage of youth passes. It is because there is no more tragic drama in your life. Instead, love enters a more mature and familiar stage.