Shogun (Asian Saga: Chronological Order #1) by James Clavell

This is James Clavell's tour-de-force; the epic saga of Pilot-Major John Blackthorne, who is shipwrecked on Japan, the most alien of shores. The novel charts Blackthorne's rise from the status of reviled foreigner up to the heights of trusted advisor and, eventually, samurai. All as a civil war looms over the fragile country.