Yoshitsune eventually made his way to Hiraizumi, Mutsu, once again to the protection of Fujiwara no Hidehira, and lived undisturbed for a time. Hidehira's son Fujiwara no Yasuhira had promised upon Hidehira's death to honor his father's wishes and continue to shelter Yoshitsune, but, giving in to pressure from Yoritomo, betrayed Yoshitsune, surrounding his Koromogawa-no-tachi residence with his troops, defeating Yoshitsune's retainers, including Benkei (in a famous "standing death"), and forcing Yoshitsune to commit seppuku. Yasuhira then had Yoshitsune's head preserved in sake, placed in a black-lacquered chest, and sent to Yoritomo as proof of his death. Historical sources differ as to the fate of Yoshitsune's mistress Shizuka and their son.