The Battle of Aizu was fought in northern Japan from October to November 1868, as part of the Boshin War. The feudal domain of Aizu was a prominent target for the Imperial Court as it was a stronghold for the Tokugawa shogunate that was renowned for its martial tradition in addition to being the birthplace of daimyo Matsudaira Katamori. The Imperial forces laid siege to Aizu to starve out the local defenders and force a surrender. After two months of constant attacks, the Tokugawa forces surrendered, sealing the fate of the samurai. The battle also resulted in the deaths of Katamori and Nakano Takeko, an onna-musha who led an ad hoc battalion of female soldiers known as the Joshitai and was a member of the Japanese Brotherhood of Assassins.
The Shiba family
As with the Battle of Toba–Fushimi, the Shiba family fought on the side of the Tokugawa shogunate. Shiba Atsuko was sent to infiltrate the Imperial camp to acquire the attack plans at the behest of the Brotherhood. Although her mission was successful, she was forced to flee after being unmasked by a camp sentinel. However, Atsuko was later caught by "Masajiro", secretly the Assassin spy Matsuo, who decided to let her go as a sign of gratitude for having spared his life during her earlier assault on the camp of British Templar William Lloyd.
After her mentor Takeko was fatally shot leading the Joshintai, Atsuko severed her head so as to prevent her corpse from being desecrated as a trophy. While leaving the battlefield, Atsuko met and fought Lloyd but was defeated and almost killed before being saved by her brother Ibuka. Overcoming his cowardice that had plagued him since childhood, Ibuka fought and slew Lloyd but was fatally wounded in the process. He managed to carry Atsuko away from the battlefield with the last of his strength before succumbing to his wounds.
Behind the scenes
Historically, Takeko was said to have been beheaded by her younger sister Yūko with the help of Ainu soldier Ueno Yoshisaburō. Additionally, Katamori survived the Battle of Aizu and later became the head kannushi of the Nikko Tosho-gu Buddhist shrine until his death in 1893 as opposed to being killed as depicted in The Blade of Aizu.