There is a legend that Kaison became immortal (survived over 400 years, although his date of birth and death unknown) and told people the Genpei War or the Legend of Yoshitsune so vividly as if he saw such incidents with his own eyes.
その後、海尊が不老不死の身となり（400年位生きていたとも伝えられている。生没年は不明。）源平合戦や義経伝説を見てきたように語っていたと伝えられている。