The Setting Sun is a Japanese novel by Osamu Dazai. It was published in 1947 and is set in Japan after World War II. Principal characters are Kazuko, her brother Naoji, and their elderly mother. The story shows a family in decline and crisis, like many other families during this period of transition between traditional Japan and a more advanced, industrial society. Many families needed to leave their old lives behind and start anew. Throughout the story, mostly through the character Naoji, the author brings up a number of social and philosophical problems of that time period.