In wartime Japan, Junko was happily engaged to marry her beloved Ken. However, Ken was suddenly deployed to the battlefield. On the day of his departure, Junko, heartbroken yet resolute, spent their final night together and gave him a blood-written Hinomaru flag as a token of farewell. Five years pass, and the war finally ends. Junko has since married Eiji, a man several years her senior, and lives a peaceful life. One day, Ken—long believed dead—returns unexpectedly to her doorstep. Overwhelmed with shock and joy, Junko breaks down in tears, leaves her husband Eiji, and resumes her passionate relationship with Ken. This single decision drags her younger sister Chieko and her husband Eiji into a spiraling tale of desire and raw emotion.