Saito leads the Shinsengumi into the Battle in Aizu. He is sent to command Masaki, a young Aizu Clan soldier, and his men. Masaki refuses to obey his orders, believing that Saito is not a warrior since he wears his swords and clothes differently. The Shinsengumi and Masaki's army attack at Shirakawa-guchi, but are forced to retreat. Later, Masaki acknowledges Saito's status as a warrior. Hijikata recovers enough to return to the Shinsengumi. They decide to attack at Bonari Pass, and again they are completely outnumbered. Masaki sacrifices himself so Saito and the Shinsengumi can retreat. The lord of the Aizu orders them to retreat to Sendai to get reinforcements while he stays behind. Saito decides to stay with the Aizu Clan and fly the Shinsengumi's banner.