In the novel, Blackthorne is described as a navigator, and the "first English pilot ever to get through Magellan's Pass". His vessel, the
Erasmus, was hired by Dutch traders in 1598 to navigate beyond the Indian Ocean and reach Japan, where he and the surviving crew are immediately imprisoned. A
Protestant like his crewmates, Blackthorne is branded as a heretic by the Portuguese
Jesuits who control all foreign trade in Japan. The Jesuits themselves hold no direct power nor the ability to kill him outright, due to their foreigner status in Japan and delicate local politics. Blackthorne is taken to Lord Toranaga (based on the historical figure,
Tokugawa Ieyasu), a
daimyō in control of the territory where the
Erasmus first landed. Toranaga quickly realizes that Blackthorne and his ship present a great opportunity, not only in his dealings with the Portuguese but also in his struggle with his main rival, Lord Ishido (based on
Ishida Mitsunari). Lord Toranaga orders Blackthorne's imprisonment, not to punish him, but to keep him out of Ishido's reach. While in prison Blackthorne meets a Franciscan priest who gives him a much greater understanding of the tumultuous sociopolitical situation in Japan, and where the Portuguese and the Jesuits fit into it. The priest also begins teaching Blackthorne the rudiments of the Japanese language. Having been told by the priest that all who enter the prison are eventually executed, Blackthorne is prepared to die when his name is called (like the historical Adams, the Japanese call him
Anjin-san - Mr. Pilot - because his English name is too difficult to pronounce, there being no sounds or characters in Japanese for much of his name). Instead, the guards take him to
Osaka Castle, where he is cleaned up and told by Mariko - the Christian wife of one of Toranaga's samurai who, like Blackthorne, is fluent in Portuguese and Latin - that Lord Toranaga wishes to know more about England and its war against the Spanish and Portuguese. As a result of a series of events, Blackthorne eventually finds himself very close to Toranaga, saving his life on multiple occasions, as he begins to understand and deeply respect Japanese culture. For his service, he is awarded the titles, privileges and obligations of
hatamoto, granted a
fiefdom as Daimyo of Kanagawa, promoted to
samurai and
commissioned a command as both Chief
Admiral of the
Kanto region and
General of the Cannon Regiment. However, to complicate matters, he starts to fall in love with the interpreter, Mariko, and they eventually become lovers. Though Blackthorne asks Toranaga to sever Mariko's marriage so she will be free to marry him, Toranaga refuses and orders Blackthorne never to speak of the matter again. In spite of this, Blackthorne becomes a trusted friend of Toranaga. At the end of the book, Toranaga defeats Ishido's forces (a reference to the
Battle of Sekigahara) and becomes Shōgun. Though Toranaga secretly had
Erasmus burned and beached, he permits Blackthorne to begin constructing another ship to keep him occupied. Around this time, Toranaga also decides that Blackthorne will never be allowed to leave Japan. It can be assumed that Blackthorne eventually died in Japan without ever returning to England. == Legacy in the
Asian saga ==