In September 826, the three provinces of Kazusa, Hitachi, and Kouzuke became Shinno-ningoku (provinces where the government posts were reserved as sinecures of imperial princes), where the imperial princes who governed were regarded as Taishu (Imperial Court appointed Governor-Generals, Senior Fourth Rank, Lower Grade), however, the Taishu stayed in the capital and did not go to the provinces, so suke (governors) were dispatched to these provinces in place of kami (directors) to act for the Taishu.
なお、天長3年(826年)9月、上総・常陸・上野の三か国は親王が太守（正四位下相当の勅任の官）として治める親王任国となったが、この当時は既に太守は都にいて赴任せず、代理に介が長官として派遣されていた。