Fujiuji was the first son of Haruuji ASHIKAGA and, as apparent from the fact that one character of his name was taken from 13th shogun Yoshifuji (later Yoshiteru) ASHIKAGA, he was the next generation of Kogakubo approved by the Muromachi bakufu (Japanese feudal government headed by a shogun) in Kyoto.
藤氏は足利晴氏の長男であり、13代将軍足利義藤（後の義輝）の一字を名乗っている事からでも明らかなように、京都の室町幕府からも認められた次代古河公方であった。