Most domain codes of the Edo period addressed practical matters of administration: taxation, land tenure, the conduct of retainers. The Aizu domain’s Kaho, drafted under Hoshina Masayuki in the mid-seventeenth century, did all of that too, but its opening article set it apart from comparable codes elsewhere in Japan. It declared, in effect, that unwavering loyalty to the Tokugawa shogunate was the first duty of every lord of Aizu, and that any successor who wavered from this duty should not be regarded as a legitimate ruler.

The remaining articles addressed more conventional territory — proper conduct for samurai, standards for officials, expectations around frugality and discipline — but they were all framed as extensions of the same underlying principle of unwavering, almost filial loyalty to the shogunate and to the moral order it represented. Successive lords of Aizu were required to affirm the Kaho upon taking office, a ritual that kept its founding principle alive well into the nineteenth century.

The code’s lasting significance became clear only two centuries after it was written. When the shogunate’s authority collapsed during the Boshin War, the Aizu domain’s leadership treated the Kaho not as a historical relic but as binding obligation, and it was this sense of inherited duty that led Aizu to resist the new imperial government even after resistance elsewhere had largely ended — a decision that brought the domain to the brink of destruction.

Sources

1. Ishii, Ryosuke, Aizu-han Kaho no Kenkyu, 1968