What is clear from the historical records is that Masashige KUSUNOKI fought together with the court during the Genko War when Emperor Godaigo raised an army against the Kamakura bakufu (Japanese feudal government headed by a shogun), joined the Kenmu Government established after the fall of the bakufu, and played an active role on the side of the Southern Court, or Yoshino Court, during the period of the Northern and Southern Courts.
史料上はっきり記されているのは、鎌倉時代後期に楠木正成が後醍醐天皇が鎌倉幕府に対して挙兵した元弘の乱において宮方に従い、幕府滅亡後に成立した建武政権に加わり、南北朝時代(日本)に南朝(日本)（吉野朝廷）方として活躍した以降である。