The island of Hokkaido, in Japan, is located near the Arctic Circle and is famous for its cold, snowy winters. In this understated drama, a celebrated writer is being shown some caves, which have glow-in-the-dark moss, by the local school headmaster. One cave has quite a history, as flashbacks show: during World War II, it was the wintertime shelter chosen by three shipwrecked sailors whose supply vessel had sunk just off the coast.