Lord Tokiasa Yarikawa was the head of Clan Yarikawa who started the Yarikawa Rebellion against Clan Shimura years before the invasion. He is only mentioned, but his rebellion explains Yarikawa's grudge and the Dance of Wrath legend.
His rebellion made Shimura the jito and left Yarikawa bitter toward Clans Shimura and Sakai. That grudge is what Jin has to overcome in The Walls of Yarikawa. The Dance of Wrath comes back in the Mythic Tale of the Spirit of Yarikawa.
Baku the Voiceless
Baku the Voiceless is a silent vendor who appears only in New Game+. You find him on the small island at the centre of Lake Izuhara, in Ariake. He sells armour, dyes, charms, hats and masks for Ghost Flowers.
Bataar
Bataar is the Mongol general behind the attack on Komatsu Forge. Jin and Yuna fight him while defending the forge in Hammer and Forge.
Bettomaru
Bettomaru is the master of the Way of the Flame who lives in a dojo at the top of Mount Jogaku. You climb through a snowstorm to duel him in the Mythic Tale The Undying Flame, and he teaches Jin the technique during the fight.
Black Dye Merchant
The Black Dye Merchant is a hidden vendor in a cave east of Kawamata Village in Kushi, Toyotama. He sells deep black armour dyes and cosmetics for Flowers.