Kokushu was one of social statuses of daimyo (feudal lords) which existed during the early modern Edo period, and it referred to the daimyo having domain of one or more provinces; another name for kokushu was "kunimochidaimyo". It was also one of the ranks which rated daimyo families, based on their places of residence and castles, into kokushu (kunimochidaimyo), junkokushu (literally, "associate kokushu"), joshu daimyo (daimyo who was allowed to live in a castle), joshu class, and mujo daimyo (daimyo without castle; "jinya"). This article describes kokushu and junkokushu. The term "kokushu" was derived from "kunimochishu" (one of honorary terms for local governors who were in hereditary vassalage to the Shogun) of the medieval Muromachi period, who were shugo (provincial constables) of large provinces but whose family lineage did not make them kanrei (shogunal deputy) or goshobanshu (members to escort the Shogun).
Since Mutsu Province and Dewa Province had vast territories, the lords in Sendai Domain (the Date clan), Morioka Domain (the Nanbu clan), Akita Domain (the Satake clan), and Yonezawa Domain (the Uesugi clan), who ruled only parts of the province, were treated as kokushu. Due to the smallness of the area, the Matsuura clan (Hirado Domain) of Iki ikkoku ichien chigyo (literally, "complete proprietorship in one province"), and the Mikawa Inagaki clan (Toba Domain) of Shima ikkoku ichien chigyo were not regarded as kokushu or kunimochi, respectively. The lord in Obama Domain (the Sakai clan) was not regarded as kunimochi in light of the balance with the head family, or the Sakai clan of the Himeji Domain, in spite of possessing Wakasa Province and Tsuruga District, Echizen Province (however, it is said that Tadakatsu SAKAI (the lord of Obama Domain of Wakasa Province) became kunimochi for one generation only by appointment by Iemitsu TOKUGAWA). Also, in spite of their high ranks, Tokugawa gosanke (three privileged branches of Tokugawa family), the Aizu-Matsudaira family (Aizu Domain), Matsudaira sanuki no kami (the governor of Sanuki Province) (Takamatsu family), and the Ii clan (Hikone Domain) were not included in kokushu or kunimochi.
Also, in some cases, the family line which was promoted to the Fourth Rank were called kokushu kaku (status of kokushu).
Standards of kokushu and kunimochidaimyo
During reigns of the family, appointment to the jiju (a chamberlain) of Fourth Rank (jushiinoge (Junior Fourth Rank, Lower Grade)) or higher. In the case of the first appointment of heyazumi (an adult-age eldest son who had yet to come into his inheritance), appointment to the jushiinoge or higher and having no other family member appointed to goi (Fifth Rank).
Upon coming and going to the capital during sankinkotai (a system under which feudal lords in the Edo period were required to spend every other year in residence in Edo), before being granted an audience with the Shogun, the family having the privilege of the Shogun's roju (member of the Shogun's council of elders) coming with the information to the daimyo's residence.
The lower limit of kokudaka (a system for determining land value for tribute purposes in the Edo period) was indeterminate.
However, there are some exceptions to the above standards.
Of kokushu and kunimochidaimyo, the families with the last name of Matsudaira other than the Yamauchi family, as well as the Hosokawa and Uesugi families who were senior vassals during the Muromachi period, had the custom of "genpuku" (coming-of-age ceremony) cerebration in the court and granting subordinates the use of a character from the superior's real name for the successors.