Lee Dong-hoon

High school student SeeWoo was playing with his younger sister, SeoYeon, at home when a water balloon that SeoYeon accidentally threw fell through the window, killing the boy who lived upstairs. The only ones who know the truth are SeeWoo and his mother. SeeWoo hesitates out of fear, but his mother strongly opposes his desire to confess.

One foggy spring day, the 12-year-old Hyeok-su meets the young Eun-hye and determines then and there that he will love her for the rest of his life. Many years later, Hyeok-su is preparing to enter college when he rescues a woman from assault. It turns out to be Eun-hye. Despite the passage of time, neither had forgotten the other and they renew their relationship. However, fate places another smitten man in Eun-hye's life. He is also determined that he will marry Eun-hye. Eventually, Eun-hye is forced to choose between them.