Yamato is the son of Kaido. Born as Kaidou's daughter and groomed from a young age to be his heir, Yamato instead developed a profound admiration for the legendary samurai Kozuki Oden. After Oden's death, Yamato decided to become like him, impersonating him and adopting his mannerisms. Yamato befriended Portgas D. Ace during his visit to Wano Country, and after learning of Ace's death waited for the arrival of his sworn brother, Monkey D.Luffy, later as time come Kaido was put down by Luffy.