Ryoke is a term used in the context of Japanese shoen (manor in medieval Japan) to represent a lord of the shoen, donated by Kaihatsu-ryoshu (local notables who actually developed the land). Powerful central nobility, temples, and shrines that were donated shoen became ryoke.
In the mid-Heian period, from the late 10th century to the 11th century, farmland development and their privatization by Tato, local powerful farmers, had been accelerated. The owners of those developed farmlands were called Kaihatsu-ryoshu. However, their status of land possession actually lacked legal foundation and was therefore quite unstable, with a high possibility of confiscation of their lands by kokuga (provincial government offices). Consequently, many Kaihatsu-ryoshu tried to retain their dominion and the right to manage shoen by donating their shoen to the powerful central nobility, temples, and shrines. Those who were donated shoen in this situation were called ryoke.
At that time, Manor Regulation Acts were often ordered by a 'new government' upon the change of the emperors, and also in many cases, kokuga did not authorize the ownership of shoen and incorporated them into Kokugaryo (territories governed by provincial government office). Sometimes, the authority of ryoke alone was not enough to maintain their possession of shoen. To cope with this situation, some ryoke would donate their shoen to more authoritative bodies like the Imperial family or Sekkan-ke (the families which produced regents). The lord of the manor on the top of this hierarchy was called honke (head family). Specifically, the honke and ryoke who had effective dominion of shoen were called Honjo. In some cases, other nobility who were granted part of the rights and profits of honjo regarding shoen were called ryoke.
Ryoke appointed Kaihatsu-ryoshu as shokan (an officer governing shoen) to play the role of local managers. Through those shokan, ryoke collected harvests from their shoen as nengu (land tax), and imposed labor service (kuji [public duties]) on the shomin (farmers living in their manor), taking those taxes as their own revenue. If they had honke, they delivered some of the revenue to their honke. Since ryoke mostly resided in the central areas, when disputes or trouble erupted in local areas, ryoke usually had shokan deal with them, or dispatched an envoy called onshi to solve the situation. In later eras, shokan began to work like samurai, and in some cases in the Kamakura period, some shokan were even appointed as jito (manager and lord of manor) by the Kamakura bakufu (Japanese feudal government headed by a shogun). Gradually, these armed shokan had come to disregard ryoke, encroaching their dominion. At the beginning of the Muromachi period, the introduction of the hanzei system (the system where the Muromachi bakufu allowed military governors or Shugo to collect half of the taxes from manors and demesnes as military funds) further encroached on ryoke's vested interests. Eventually, shoen were demised by taiko kenchi (the cadastral surveys conducted by Hideyoshi TOYOTOMI), leading to extinction of the position of ryoke as well.