The Samurai by Barry Sadler (Casca Series, Book 19) from Books In Motion.com

Casca Longinus. Cursed by Christ on Golgotha. Condemned to outlive the ages, and wander the globe a constant soldier. Forever fighting and surviving, he must wait for Christ to return. Feudal Japan: A forbidden island, where honor is a warrior's prized possession, and his sword a swift and deadly instrument of pride and vengeance. Casca joins forces with the legendary samurai warrior Muramasa. Together they embark on an odyssey of bloody conquest...a journey that ends in the savage fury of samurai against samurai. Read by Gene Engene.