Shogun by James Clavell

Shogun is a 1975 novel by James Clavell. Shogun is the first novel (by internal chronology) of James Clavell's Asian Saga. A major bestseller, by 1990 the book Shōgun had sold 15 million copies worldwide. Beginning in 1600 in feudal Japan, some months before the critical battle of Sekigahara, Shōgun gives an account of the rise of the daimyo "Toranaga" (based upon the actual Tokugawa Ieyasu) of the Shogunate, seen through the eyes of an English sailor whose fictional heroics are loosely based on William Adams's exploits.
Japan in 1600 is a feudal country in a precarious peace. The imperial heir is young and power rests in a council of regents formed of the most powerful overlords perpetually jostling for power and the title of Shōgun (hereditary military ruler). Japanese society is insular and xenophobic with outsiders greatly distrusted and restricted. The Catholic Church, principally through the Jesuits and other monastic orders, have gained a foothold and seek to extend their power. Guns are little used and despised, making the military capabilities of the Europeans highly desirable but risky.
John Blackthorne, an English pilot serving on the Dutch warship Erasmus, is the first ship from a Protestant country known to reach Japan. It is shipwrecked on the coast. He and the few survivors of his crew are taken captive under the direction of the local samurai Kasigi Omi. Their foreignness, and their conduct (which is seen as barbaric and disrespectful) leads Omi to imprison them in a pit until the arrival of his daimyo (feudal lord), Kasigi Yabu. (Summary by Wikipedia)