Ji-ho is a promising pianist, studying and playing abroad for years. But one night she had a stage fright and never recovers. In despair, Ji-ho comes home and meets her old classmate Sung-ryong.
Once a very bright boy, Sung-ryong had an accident and now he is in late 20's with the mind of a six year old. He is very forgetful, but he has never forgotten his first love Ji-ho. Other half of Sung-ryong's dumb mind is occupied with his only family, younger sister Jee-in. To take care of her, Sung-ryong sells toasts in front of Jee-in's school. But Jee-in is embarrassed of her idiotic brother and ignores him.
And Sang-soo is Sung-ryong's old friend who understands Sung-ryong's innocent mind. But he inevitably falls to the world of gangsters. Ji-ho is still in her slump, Jee-in falls sick and Sang-soo gets involved in a bloody dispute. But all of their agonies are miraculously saved by Sung-ryong in a way nobody has foreseen.
Unlike most of Korean movies, this is fast paced. You'll never get bored with long dragging drama scenes. You'll be moved by many touching scenes showing how loving of a person Sung-ryong is.