In 1945, the cherry trees planted by Tetsu Eren (Sayuri Yoshinaga) with great care bloomed in Karafuto. These were the seeds brought back from Japan by her husband Tokujiro (Hiroshi Abe). In August, the Soviet Union invaded southern Karafuto, and Tetsu and his sons fled to Abashiri, Hokkaido. They lived in poverty in the cold weather, but Tetsu always protected his children and raised them. Time passed, and in 1971, the grown-up second son Shujiro (Masato Sakai) and his wife Mari (Ryoko Shinohara) returned to Japan from the United States with successful careers. After a long separation, Shujiro felt quite uneasy about his elderly and slightly strange mother. At this time, the door of forbidden memories hidden in the hearts of mother and son was about to be opened.