Provincial officials in Classical Japan
 were provincial officials in Classical Japan. They were nobles sent from the central government in Kyoto to oversee a province, a system that was established as part of the Taika Reform in 645, and enacted by the "Ritsuryō" system. There were four classes of "kokushi", from the highest to the lowest: Kami (守), Suke (介), Jō (掾), and Sakan (目). In the Middle Ages, an acting governor called "mokudai", the "daikan" of the "kokushi", took over the local government of the province, while the "kokushi" returned to the capital to take on a supervising role.
History.
The oldest reference to the term "kokushi" appears on the Seventeen-article constitution from 604. As part of the Taika Reform in 645, a new system of provincial government was established, marking the beginning of the "kokushi". Before this, the governors were called "mikotomochi" (宰 or 使者). This term was replaced with the "kanji" characters 国 (province) and 司 (governor), and thus became known as "kokushi".
The "kokushi" were divided into four classes (四等官, "sitōkan"), from the highest to the lowest: "Kami" (守), "Suke" (介), "Jō" (掾), and "Sakan" (目). Japan was divided into 66 provinces and two islands, and the number of "kokushi" officials and classes appointed to each province depended on which of the four provincial classes ("dai", "jō", "chū", and "ge") it belonged to.
They held considerable power, as they were in charge of the administration, finance, law, and military of the province. In the beginning, the term of office was six years, but later reduced to four years, with the exception of some special provinces. During the tenure, the "kokushi" received income through tax collection, and later received financial privileges that central government officials did not receive. As the "ritsuryō" system began to decline, the position of "kokushi" was seen as one type of income source.
In September 826, princes of the Imperial Family were appointed as "kokushi" in Kazusa Province, Hitachi Province and Kōzuke Province. These "kami"-class "kokushi" were called "taishu", and as they did not leave the capital and work at their assigned province, provinces with no local governor were born. In contrast to this, "kami" who left the capital to occupy their local office became known as "zuryō".
After the 10th century, following the instability and dissolution of the "ritsuryō" system, the former duties of district governors ("gunji") and lower officials were taken over by the "kokushi", making the "kokushi" even more powerful.
However, in response to the rising power of the "kokushi", the district governors and commoners began fighting against the "kokushi". Due to the ever strengthening resistance, the "kokushi" returned to the safety of the central government in Kyoto and appointed an acting governor ("mokudai"), the "daikan" of the "kokushi", who governed the province locally while the "kokushi" took the role of a supervisor.
Following the establishment of local governments ("rusudokoro") of the "mokudai" and the installation of provincial fiefdoms ("chigyōkoku"), the "kokushi" became a new category of manorial lords. As the "Sesshō" and "Kampaku" and Great Council Ministers were allowed to fill any vacant "kami" posts, and send their private deputies, the "mokudai", to take care of the practical governing duties, the whole system of "kokushi" became increasingly corrupt. As the mokudai were also appointed from powerful local clans, the provincial government was drifting increasingly farther away from the central government in Kyoto.
After the Heian period, the highest official, "kami", became also known as zuryō (). The term originally meant the change of office to a newly assigned "kokushi".
In the Kamakura period, following the establishment of the Kamakura shogunate, the samurai formed their own provincial government, the "shugo" who were appointed by the shogun and shikken in contrast to the "kokushi" who were appointed by the Imperial Court. The "shugo" gradually usurped power away from the "kokushi", becoming the "de facto" governors while the "kokushi" remained the "de jure" governors, though powerless titleholders in practice.
Even after the abolishment of medieval manors, politically, the "kokushi" remained as an honorific title until Meiji Restoration in 1868.