Legend holds that Masakado had come to be referred to by the title Hinomoto Shogun TAIRA no Shinno at the time that the military epic, "Gen-pei Tojoroku," was completed, which is considered to have been written in 1337 at the latest.
遅くとも建武(日本)4年（1337年）には成立したと見られている軍記物語『源平闘諍録』以降、将門は日本将軍（ひのもとしょうぐん）平親王と称したという伝説が成立している。