Masayoshi expanded his power outward from Satake-go, Kuji County, which he had inherited from his father, and submitted the Onozaki clan (Fujiwara clan of FUJIWARA no Hidesato house), who had traditionally settled in Hitachi Province, and further promoted his dominance in seven counties of Oku-Hitachi.
昌義は父から継承した久慈郡佐竹郷を中心に勢力を拡張し、旧来から常陸国に土着していた小野崎氏(藤原秀郷流藤原氏)などを屈服させ、奥常陸7郡の支配をさらに進めた。