Osamu Dazai's masterpiece, 'The Setting Sun,' chronicles the decline of the Japanese aristocracy in the immediate aftermath of World War II. The story is told through the eyes of Kazuko, a young woman from a noble family, who struggles with the loss of their status and wealth. It is a profound and melancholic exploration of social change, family disintegration, and the desperate search for individual purpose in a world stripped of its traditional values, making it a cornerstone of modern Japanese literature.