Rusui (a governmental post placed in the Edo bakufu and in domains) (留守居)

Rusui was a governmental post placed in the Edo bakufu and in domains. It was also called Orusui.

Rusui officers of domains were also called Oshirozukai (literally, an officer at the castle) in Edo, established a Rusui association approved by the bakufu to exchange information, and therefore, they were so-called diplomats of domains.

In a few domains, the Rusui officer, being responsible for guarding the lord residence in Edo while the lord was absent from there, and the Oshirozukai liaison officer were placed separately.

A deputy Rusui officer or an assistant to a Rusui officer was often called Rusui-soeyaku.

Rusui in the bakufu

Rusui officers, being under control of Roju (the second-highest post in the bakufu government), controlled O-oku (inner halls of the Edo castle), managed the travel certificates, and played the role of guarding the Edo castle while Seii taishogun (literally, "the great general who was to subdue the barbarians") was out of the castle.

Selected from Hatamoto (direct retainers of the bakufu), each of the officers earned a 5,000 koku of rice crop (approx. 180 liters/koku) for the post, being the highest level available for Hatamoto. In the early Edo period, the "O-rusui" post for the leader of the Rusui officers was established, for which the highest social status available for Hatamoto was given. However, as the occasions when a shogun became absent from the Edo castle diminished and power was transferred to lower-level posts due to the improvement of the bakufu system, the social status level of this post declined. In around the Genroku era (1688 - 1704), this post became a Honorary one for the Hatamoto who were loyal to the bakufu for a long period of time.

It should be noted that there was a similarly named post of Rusuiban. The officers in this post, being under control of Roju as Rusui officers, guarded O-oku over night and did chores in the O-oku area. Hatamoto with roughly 5,000 koku of rice crop were appointed to this post. The officers in this post were associates of those in Rusui post, but they were not in the master-servant relationship.

Rusui in domains
Many of the Rusui officers in domains were selected from competent retainers in the Monogashira (military commanders) class (the banto (head of a group) class in smaller domains)

The Rusui officers were responsible for guarding the domain residence in Edo while the lord was absent from the residence. In addition, the officers stayed in the sotetsu (cycad) room in the Edo castle as the Oshirozukai officers to grasp movements of the cabinet officials of the Shogunate, to obtain and interpret various laws and regulations presented by the bakufu and to compose documents to be submitted to the bakufu.
Furthermore, with so many behavioral styles, so called "three hundred etiquette styles and three thousand ritual styles," established in the Edo period, it was considered that the largest importance should be placed on following precedents correctly
To search for the precedents supporting the practice, information was exchanged among these officers in the Rusui association.
It was also a role of Rusui in domain to make communications and adjustment between the main domain and its branched domain

Hating secret maneuvers by Rusui officers of domains, the bakufu prohibited them from entering the Edo castle several times, but the prohibition was released each time soon because the measure caused inconvenience. This fact would reveal their delicate position.

Rusui officers exchanged information frequently at yukaku (red-light districts) or restaurants, neglecting the financial situations of their domains. Therefore, their behaviors were viewed indignantly by their domains suffering from financial difficulties or by the financial officers concerned.

When a domain had its own residence in Kyoto, Osaka, or Nagasaki, Rusui officers were mostly placed in these residences as well.