Yoshiaki ASHIKAGA, a younger brother of the third Koga Kubo, Takamoto ASHIKAGA, proclaimed himself Oyumi Kubo at the Oyumi-jo Castle in Shimousa Province supported by the Kazusa Takeda clan (the Takeda clan) who was the lord of the Mariyatsu-jo Castle in Kazusa Province.
3代古河公方足利高基の弟足利義明が上総国真里谷（まりやつ）城主の武田氏上総武田氏に擁立されて、下総国の小弓城で自称したもの。