Mister Kim lives in Nippontown and is a leader at the local Yakuza branch. He likes to make an impression and tease people. He doesn't look much like a tough person or not so serious, but he can be very "persuasive" when he wants.
Book 1: The World Awakens
He had a turf war against the Triad, and the Golden Snake, but made peace with them. He helped the Tsukikage fight against the cultists from the Red Hand in the day of Red December.