Hachi is the brother of Sadao, one of the conspirators responsible for the Adachi massacre. He assists his brother in his work and later murders Sadao's wife, Hina, to silence her.
In The Headman, Hachi is using a cart to bring supplies to other camps. Jin Sakai and Lady Masako follow him to meet his brother, but before he arrives at his destination, Hachi is stopped by some bandits and made to hand over sake in his cart. He says that he does not have sake, but he does have a note for Sadao. The bandits tell him to go on his way, and his tailers follow the bandits instead.
In The Husband, Hachi is ordered to kill Hina but tries to save her, but ends up killing her because she was screaming for help. He runs away and is attacked by Mongols; his tracks are followed by Jin and Masako, who kill the Mongols. He explains how he was trying to help Hina, and then dies from his wounds.