The era is in the midst of war. Masako (Aki Ko Kishima), who was about to marry her betrothed Ken, was at the height of happiness. But Ken went off to war. As Masako sees Ken off, she bites back the sorrow in her heart and spends their last night together, handing him a blood-written Hinomaru flag. Five years later. After the end of the war, Masako marries Eiji, a man several years older than herself, and lives a comfortable life without any hardships. One day, Ken, who was reported to have died in battle, returns to Masako. Overwhelmed with shock and joy, Masako, despite being married, ends up having a relationship with Ken. This becomes the trigger for a lascivious chain of events that also involves Masako's sister Chieko and her husband Eiji…
