The ji-zamurai (地侍?), also known as kokujin (国人?), were lords of smaller rural domains in feudal Japan. They often used their relatively small plots of land for intensive and diversified forms of agriculture; the kokujin sought to be as productive and self-sufficient as possible, hoping to gain wealth and power. Independent and strongly attached to their land, many kokujin formed leagues for common defense called ikki, and took part in the agrarian uprisings of the 16th and 17th centuries as well as quite a number of earlier events.

One of the primary causes for the rise in the number of smaller land holders was a decline in the custom of primogeniture. Towards the end of the Kamakura period, inheritance began to be split among a lord's sons, making each heir's holdings, and thus their power, smaller.

Over time, many of these smaller fiefs came to be dominated by the Shugo, Constables who were administrators appointed by the shogunate to oversee the provinces. Resentful and mistrustful of the interference of government officials, they banded together into leagues called ikki. The uprisings that resulted, particularly when the Shugo tried to seize control of entire provinces, were also called ikki; some of the largest and most famous took place in Wakasa province in the 1350s. In addition, the kokujin represented a considerable force during many of Japan's wars. Despite their lowly stature individually, the ji-samurai were a considerable portion of the noble (warrior) class, and their favor could often decide a battle or a war.

Kokujin were sometimes also referred to as dogō, representing their importance in rural life. They might have held lands worth, on average, fifty koku and, though their holdings were small compared to some other lords, they still required extra hands to help tend the fields. Peasant workers, called hikan or nago, often holding small areas of fields themselves, would be hired, and would often live very near the lord's home in the village. Even some of the smallest of these rural villages would be arranged like miniature fortresses, with walls or even moats around the lord's home, and another wall around the main section of the village. This arrangement between peasant workers and kokujin landlords became more complicated after the imposition of a land survey, census, and taxation by Toyotomi Hideyoshi at the end of the 16th century, and many peasants gained greater independence, but the system remained in place for the most part.