After Ogami Ittō's wife Azami gives birth to their son, Daigorō, Ogami Ittō returns to find her and all of their household brutally murdered, with only the newborn Daigorō surviving.
Toward the end of their journeys, Ogami Ittō's dōtanuki sword is surreptitiously damaged by a supposed sword-polisher who is really an elite "Grass" ninja of the Yagyū clan.