The fifth kubo, Nariuji ASHIKAGA competing with Muromachi bakufu ran away to Koga of the Province of Shimousa (Koga City, Ibaraki Prefecture) in 1455 and, since then, became Kogakubo (descendants of one of the Ashikaga families that held the office of the Kanto district administrator).
康正元年（1455年）、5代公方の足利成氏は室町幕府側と対立し、下総国古河（茨城県古河市）に逃れて、以後「古河公方」となる。