This Noh play begins with MINAMOTO no Yoshitsune escaping to Saigoku (the western part of Japan [a region including Kyushu, but ranging as far east as Kinki]) because he was viewed with suspicion by MINAMOTO no Yoritomo after subduing the Taira clan.
源義経が平氏を討伐したのち、源頼朝に疑われて西国に落ちるところからこの能ははじまる。