Niru

Niru [にる] was the general name given to administrative divisions of the Summui Kingdom, whether they be a district, town, village or island, as established by the Kingdom throughout the Honnan region. Niru were created as a way of maintaining control over the Summui population, along with making it easier to develop different areas within the Kingdom.
From the 1100s onwards, three main districts (oniru) were established, which would later become the prefectures we know today: Tonnori (now Zōhai), Fuzai (now Uchi) and Muishō (now Inaki). There were around 600 jan, or townships, scattered across these districts. In concept these jan were similar to the provinces established on the Kantonese mainland, but in terms of population they were closer to villages. A cluster of 20 jan became a ojii and had one taro, which might translate to 'overseer', 'lord' or 'governor'. These taro were under the command of the King, but also had their own freedoms and could generally govern their ojii however they wished. Very high-ranking taro could be promoted to onirutaro and become a governor of one of the three oniru. Until the 1500s, when land reforms were put in place, taro would often battle for control of more land, and boundaries were constantly shifting. For this reason, very few niru maps exist from before the 16th century.
Along with oniru, ojii and jan, there was a special allowance for islands, the main two being Shimi and Kihata, which were considered under the direct control of the King himself and therefore exempt from land claims. Until the 1500s, these islands (Shimi and Kihata being the largest, although there are many smaller ones scattered off the shores of Daizō) were very sparsely inhabited and often used as places of inprisonment or banishment.