The Spirit of Yarikawa's Vengeance is a masked warrior from Clan Yarikawa who answers prayers for revenge with the Dance of Wrath technique. You hunt the Spirit in the Mythic Tale The Spirit of Yarikawa's Vengeance to learn that technique.
The Spirit serves Yarikawa's interests, killing Mongols and settling personal scores alike. Some of its writings suggest it is stirring up the people's hatred of the Sakai and Shimura clans.
The Spirit is a woman of Clan Yarikawa. She meets Jin in a ritual duel and dies. Jin vows to use the Dance of Wrath against the Mongols instead.