Born in Osaka to parents of Jeju origin, Kim accompanied his family to Jeju, a Korean island, where he became acquainted with supporters of the Korean independence movement. In 1945, when he had returned to Osaka, the war ended. Directly after that, he went to Seoul, but came back to Japan again after that, where he would stay. He attended Kansai University, and graduated from the Department of Literature at Kyoto University, having specialized in literature. Soon after his graduation, the April 3 massacre broke out in his ancestral hometown of Jeju, an incident which became a motif of his later work.