Purity.

This drama depicts four people who are in love with each other and face various kinds of difficulties that arise from the twist of fate, the choice between love and friendship, and the fear of love. They finally overcome their obstacles through understanding each other and realize that love can be in its true form when it is 'pure' not shadowed by jealousy and hate. One day, Jin Woo, a 7-year-old boy, gets glad to see Eun Hee (Hae Jin in later years) who came to live with him, but three month later, Jin Woo reluctantly had to let Eun Hee leave for her uncle's. Twenty years later, Hyun Seok, kind of a playboy, shares his umbrella with Hae Jin who was worried about going home in the rain at the radio station. Jin Woo, now a director working at the radio station, falls in love with Hae Jin, a writer, at a first sight. [Source: korean-drama-guide.com]