The last assault of Aizu Jōshigun (also called Jōshitai, Women Battalion) against Imperial Forces.
The character Asai Sayoko is a dramatic depiction of historical figure Nakano Takeko (中野竹子).
It is deemed historical that on her death, Nakano had her head cut off by her companions, to avoid it being taken as trophy by the enemy. Here, it is Sayoko’s own mother who takes on this terrible duty.
from “Byakkotai” (白虎隊) 2007
Please read more about Nakano Takeko and her later called “Jōshitai”, The Boshin war and the Battle of Aizu.