The story is about a cheerful high school student named Han Ye-won.
She is a sweet, clumsy and warm girl. On the other hand, there is Ji Eun-sung , a student from a vocational school and a well-known bully. He is hot-tempered and rude but deep inside he longs to be loved.
One day, clumsily, Ye-won leaves a message on the school website to reply to Eun-sung's impolite message. She is shocked when someone calls her cell phone and threatens her. Gradually, her best friend, Lee Kyung-won, tells her who Eun-sung is. He sends Ye-won a text message: He will wait for her in front of the main gate. She is so scared that she and Kyung-won decide to jump over the school wall. Unfortunately, the moment Ye-won jumps, Eun-sung is standing exactly at the other side of wall. She falls on him and their lips meet accidentally. Raising his voice, Eun-sung asks her to take responsibility; she is astonished. His friend explains that Eun-sung has never even held hands with a girl. Since she is the first girl who kissed him, as a consequence, she must marry him.
Events happen quickly. At the beginning, Ye-won does not have any feelings for Eun-sung. She even rejects his invitation to come to his birthday party. Unknowingly, Eun-sung has fallen in love with her; but he is not the kind of guy who knows how to express his feelings. He is jealous when Ye-won is approached by other guys but he does not know how to be with someone he loves. Although he is rude and bad-tempered, Eun-sung always pardons Ye-won's faults and clumsiness. However, he can't bear it when he finds out that Ye-won went out with Kim Han-sung ,
an older student whom he hates. Broken-hearted, Eun-sung decides to leave Korea and follow his mother to the USA.
A year later Ye-won is seen with Han-sung, discussing whether she is scared for her college entrance exams. During the listening portion of her exams, a quote from Romeo and Juliet
is mentioned, making Ye-won recall the memory of her and Eun-sung in the park where they promised that no matter what, they would reunite in front of the telephone booth at the first snowfall. Ye-won stops what she is doing and runs to the park. She waits there as the scene rolls back to the fantasy she had a year ago and she starts to cry because Eun-sung is not there. As she turns around, a rabbit is hopping towards her, the same rabbit she gave to Eun-sung as a gift. She looks up and Eun-sung is there. She yells at him, saying, "Why did you leave without saying goodbye?" And Eun-sung replies, "True love requires no words." Ye-won runs to him and they embrace.
The film ends with Eun-sung's childhood memory of some opening event of an elementary school where the only kid that would kiss Eun-sung was Ye-won. An interesting aspect to this is that earlier on in the film, Ye-won uses Eun-sung's cellphone to make a mini-video of her bedroom. There she captures footage of an old photo from when she was little, showing her and a friend. It turns out that this friend is actually the little Eun-sung, hinting at the connection between the two. When Eun-sung watches the video on his cell phone towards the end of the film, he is surprised to see himself and remembers that Ye-won was that little girl.
