Soon after, Masakado intervened in a tense dispute involving the Zuryo (the Provincial Governors) and the local Fugo-so (the upper class) who were at war with the Kokuga (the provincial government office); the intervention was considered to be an act of rebellion against the Imperial Court.
やがて受領と地方富豪層の間の緊張関係の調停に積極介入するようになり、そのこじれから国衙と戦となって、結果的に朝廷への叛乱とみなされるに至った。