In the 19th century Edo period, sisters Oshizu and Otaka have sacrificed their personal happiness to work and care for their ailing father. Otaka falls in love, but can’t accept a marriage proposal since her older sister needs to marry first. When Oshizu learns of this decision, she takes matters in her own hands.

The last film in the series brings the tale to the doorstep of Pacific War, with the planning of the bombing of Pearl Harbor dominant in Nakano Spy School.