One day, Ji Hwan begins to receive letters from an unidentified person. The letters, containing black-and-white photos of happy children playing, remind Ji Hwan of his old two friends.
Five years earlier, while Ji Hwan is taking pictures with his camera, two girls, Soo In and Gyung Hee, walk into the frame. Ji Hwan falls in love with Soo In at first sight. He then musters up enough courage to confess his love to her, but she refuses him very politely. Even so, Ji Hwan doesn't give up and tells them that he wants to be friends the next time they meet.
Ever since then, the three of them start a wonderful friendship. They spend time each other always and consider it the most precious moments of their lives. But they become confused between love and friendship and, finally, Gyung Hee and Soo In leave him without a trace.
The random letters inspire Ji Hwan to depart anxiously on a long journey to find his old friends, but while looking for Soo In and Gyung Hee, he confronts a beautiful yet sad secret.