Blackthorne, in turn, teaches Toranaga about European tactics, cannon-making, and the treachery of the Portuguese. He also gives Toranaga a crucial political weapon: the concept of a "Protestant" alternative to the Catholic powers.
Ishido demands that Toranaga come to the capital, Osaka, to answer for his "treason." If Toranaga goes, he will be killed. If he refuses, the coalition will attack. Toranaga uses Blackthorne’s knowledge to secretly arm his own ships and plan a daring escape. Shogun
Japan is on the brink of civil war. The elderly (the former regent) is dead, leaving a child heir. A Council of Five Regents rules in his name, but the regents are deeply divided. The most powerful and ambitious is Lord Ishido Kazunari , who wants to become the next Shōgun (military dictator). The only regent strong enough to oppose him is Lord Yoshi Toranaga , a brilliant and cunning strategist. If he refuses, the coalition will attack
Blackthorne, now a broken but wiser man, is offered a choice: he can return to England on a new ship, or stay in Japan as Toranaga’s permanent vassal (a hatamoto —a direct retainer). He chooses to stay, partly because he has nowhere else to go, but mostly because he has found his soul in Japan. The elderly (the former regent) is dead, leaving
In Osaka, Mariko becomes a heroine. She refuses to bow to Ishido, confronts the Jesuits, and demands her right to leave. When Ishido surrounds her with soldiers, she walks calmly to the castle gate. The standoff ends in chaos: assassins sent by the Jesuits (or by Ishido) attack. Mariko is mortally wounded while shielding Blackthorne and Toranaga’s family. Her death is the ultimate act of giri —duty to her lord—and her final rejection of Ishido’s power.