Arisaka was a Senshi under Emperor Shigeru in Nihon-Ja, one of the antagonists in Book 10.


Arisaka is
Emperor Shigeru

Emperor Shigeru who Arisaka attacks

the Lord of the Shimonseki Senshi clan.

When the Emperor before Shigeru died without an heir, Arisaka believed that he should have been made Emperor instead of Shigeru. He then began fostering a whispering campaign for months, spreading rumors and fear among the Senshi that Shigeru was going to take power from them and give it to the common people, which made the Senshi scared.

Arisaka got his clan and another of the more powerful Senshi clans to rebel by claiming the Emperor has disobeyed an oath by trying to raise up commoners against their betters when he was really just trying to improve the workers lives. Some of the Senshi, being proud and even arrogant warriors, joined in the revolt with Arisaka as their leader.

Arisaka followed Shigeru, who was on the run, to the legendary fortress of Ran-Koshi, located in northern Nihon-Ja, and there he laid seige to the valley throughout the winter along with his army. 

On the way Shukin, the cousin of Shigeru, stays behind at a valley with several men to try and slow down Arisaka's army.  However, he is defeated then killed by Arisaka who does not spare his enemies.

The rebel lord then engaged the help of other senshi lords by lying to them, saying that an imposter had taken the place of Shigeru and that he was trying to defeat this so-called imposter who was just Shigeru. 

Arisaka is furious after he loses his first attack at the start of the siege.

He was enraged when he was defeated, as Shigeru offers to stand down to end the bloodshed after a series of battles. The Senshi who had rebelled realized how honourable the Emperor was and stand down themselves. After Will insults and goads Arisaka, he tries to attack Will, but Will kills him with an underarm Saxe Knife throw.