Nenryo Zakki (年料雑器)
Nenryo zakki was earthenware from Owari Province and Nagato Province appointed by the central government as payments of tribute under the Ritsuryo system (a system of centralized government based on the ritsuryo code). In some cases, nenryo zakki referred specifically to ryokuyu toki (green-glazed ware).
Glaze techniques were considered so valuable in ancient Japan that they were put under the control of the government. Influenced in particular by the Chinese continent, ryokuyu toki was so popular among nobles during the Heian period that production in the government craft centers established in the Kinai region (the five capital provinces surrounding the ancient capitals of Nara and Kyoto) were unable to keep up with demand. As a result, both the Owari Province and Nagato Province as principal production areas of earthenware at the time in Japan, were ordered to make tributes of their products. Accordingly, earthenware prepared as nenryo zakki was also produced in craft centers under direct control of the kokufu (provincial offices). The necessary expenses for the production, such as material costs, were subsidized by shozei (rice tax stored in warehouses of provincial offices).
The Engishiki (codes and procedures on national rites and prayers) stipulated size standards for earthenware, such as the diameter of owan (large soup bowls) as 289mm, nakawan (medium-sized soup bowls) as 212mm, showan (small soup bowls) as 182mm, kaban (plates with a floral pattern with legs) as 167mm and hanagataenbai as 91mm.