A simple OC Character named Tsutomu Ichikawa. Thanks to Zac for the character's name and backstory.
Backstory: A swordsman called Tsutomu Ichikawa was kicked out of his turf in Tokyo by an agressive Hiroshima Yakuza after the bombing, so he fled with his patriarch to Osaka and helped him found his own Yakuza Family. Ever since, he's resentful of Tokyo Yakuzas who took his turf and want to settle things by defeating their champions