The opening starts with the introduction of a genius. At 17, Tae Woong (Hyun Bin) meets two people who will later become people he loves. One becomes his best friend and the other, his love.
The guy he meets is Kim Jeong Kyu Lee Sun Ho also classified as a genius, and though at first they did not get along, they soon set aside their differences and became best friends. Jeong Kyu tells Tae Woong about a girl he admires and promises to introduce him to her. When Tae Woong asks him why Jeong Kyu won't ask the girl out himself, Jeong Kyu says that he doesn't have time if he wants to win the award in math for the Nobel Peace Prize; his dad's dream and his.
Tae Woong meets a little girl being bullied by older girls for her money and saves her. The girl develops a crush on him and gives him her beeper for future contact. She later contacts him and he finds out that she was running away from home, and for a day the two run away together to an amusement park. She gets into a cab to go home but reminds Tae Woong that he never found out her name.
Later on, Tae Woong and Jeong Kyu both enter an international math Olympiad that Jeong Kyu and his father want to win badly. When Tae Woong wins, Jeong Kyu commits suicide.
The following tragic events soon took its toll on the rest of Tae Woong's life, and forgets about ever set a date to meet the little girl. Then, for 8 years he struggled to carry on with his life.
At 25, Tae Woong is now a third class boxer and in unexpected events, finds Bo Ra (Sung Yu Ri), the little girl he once knew.
The tale continues into the world of the cold-hearted Bo Ra and it is only Tae Woong that could possibly melt her heart. It slowly unfolds many secrets along the way and the past is soon to be made right again. With the help of Tae Woong's love, Bo Ra learns to find happiness within herself, and in return, Tae Woong comes into terms with his past.
Although this winter will be very cold and scary, winter is not the end of the seasons, but the beginning of the hope for a greater love.
Hyun Bin as Han Tae Woong/Han Deuk Gu
Sung Yu Ri as Kim Bo Ra
Im Ju Hwan as Suh Gun Woo
Yoo In Young as Lee Seung Ri