Man with No Name by Laird Barron

Nanashi was born into a life of violence. Delivered from the mean streets by the Heron Clan, he mastered the way of the gun and knife and swiftly ascended through yakuza ranks to become a dreaded enforcer. His latest task? He and an entourage of expert killers are commanded to kidnap Muzaki, a retired world-renowned wrestler under protection of the rival Dragon Syndicate. It should be business as bloody usual for Nanashi and his ruthless brothers in arms, except for the detail that Muzaki possesses a terrifying secret. A secret that will spawn a no-holds barred gang war and send Nanashi on a personal odyssey into immortal darkness.