"Kokujin" are the samurai class, mainly originating from the jito (manager and lord of manor) class in the Kamakura period, who engaged in the development of provinces from the period of the Northern and Southern Courts (Japan) to the Muromachi period. Kokujin ryoshu (local samurai lord). Kunishu or kokujinshu, when referring to them collectively.
Kokujin is a general term used for the shokan (an officer governing shoen), gunji (district chief), goji (hamlet chief), and hoshi (chief of imperial fief) ranks who became managers of shoen (manor in medieval Japan) and kokugaryo (territories governed by provincial government office) under the late dynasty state system established in the middle of the Heian period, and the feudal lords in the province who belong to the family tree of the jito since the Kamakura period who often originated from there, and is a term used for documentation at that time. It was used to refer to the residing forces who were in rivalry with outside rulers such as the bakufu (Japanese feudal government headed by a shogun), shugo (provincial constable), and manor lords, and who aimed for their own regional dominance.
The name 'kokujin' is found here and there, since the Kamakura period, as a word referring to 'samurai with their own power centered around a chief residing in the area.'
Their direct origin are the samurai who were jito during the Kamakura period, who indigenized and became resident feudal lords. During the Kamakura period, they were sometimes referred to as 'akuto' (rebels), implying they are rebellious against the rulers.
It was around the time from the fall of the Kamakura bakufu (Japanese feudal government headed by a shogun) to the period of the Northern and Southern Courts (Japan), and especially after the Kanno Disturbance, that this class of samurai became significant. During the period of the Northern and Southern Courts (Japan), provincial politics and military affairs were led by feudal lords based in the province. However, kokujin responded acutely to movements in the central political arena. Kokujin rose to become a residing force with power reserved to influence the actions of the Muromachi bakufu, shugo daimyo (Japanese territorial lord as provincial constable), and manor lords. Behind this were the strengthening of the rule against the farmers which arose during the turbulence of the South and North Courts, opposition against ruling and intervention by Muromachi bakufu and shugo daimyo, and the expansion of a distribution economy and the local economy due to development of transport businesses such as bashaku (shipping agents who used horses) and toimaru (specialized wholesale merchants.
Regarding the management of their territory, the kokujin ryoshu who were resident feudal lords in a province or region, advanced from a jito feudal lord-style governance where they would rule regions by scattering in places, to a central regional governance centered around the original fief. The kokujin class intervened in conflicts between the manor lord and the jigenin (a lower rank of ancient Japanese nobility), and at times, undertook posts such as daikan (local government representative) and shomu (land management). Regional governance by kokujin ryoshu was stronger against land and farmers compared to governance by the resident feudal lords before them. Such examples are kenchi (land survey) and hitogaeshi (people who had moved to other land and then returned to their original land according to agreements between feudal lords) agreements between kokujin.
Kokujin sometimes were subordinates of external rulers such as shugo and manor lords, and were subject to subordinate-like ruling, but at times were rebels backed by a strong military force gained by subordinating the jizamurai (local samurai), who were at the upper level in the peasant class within their territory, and by coordinating with other kokujin. Kokujin-ikki (riots by kokujin) that occurred frequently from the period of the Northern and Southern Courts (Japan) to the Muromachi period, varied in style, but can be seen as uniting kokujin ryoshu.
In the Sengoku Period (Period of Warring States) (Japan), in regions where the reign of the shugo daimyo withered, kokujin existed as independent feudal lords owning castles. Like the Kiso and Murakami clans, most kokujin were incorporated into the vassalry of the daimyo (Japanese territorial lord) during the Sengoku Period. Meanwhile, some kokujin with daimyo-class power, such as the Mori clan, Chosokabe clan, Ryuzoji clan, and Tamura clan, became daimyo during the Sengoku Period. In addition, like the 15 Chikugo castles under the rule of the Otomo clan, some fell under the control of, but not necessarily becoming the vassal of a more powerful daimyo during the Sengoku Period, and maintained independence like a daimyo with management of the territory, while being militarily submissive.