In the Portuguese great cabin, Toranaga demands cannon to clear “pirates” at the harbor mouth. He dismisses talk of open war, insisting politics require deniability, and orders Father Alvito to translate exactly. Through Alvito and the Visitor dell’Aqua, Toranaga hints at expanding trade and offers a major concession: a Christian cathedral in Yedo, if the Church aids him within forty days.

With guards dismissed, Alvito and dell’Aqua swear by the Cross to try to sway Kiyama and Onoshi, and Toranaga promises the cathedral’s foundation on day forty-one. Alvito proposes secretly supplying cannon, but Ferriera reveals the galley can’t mount them without refit. The priests beg help; Ferriera agrees only after extorting concessions, including next year’s command, guarantees, higher cargo share, protection from ecclesiastical sanctions—and the heretic Blackthorne.

Meanwhile Mariko finds Blackthorne drunk and sick from gorging and drink. Bosun Manuel Pesaro insults her and Kana, even propositioning her; Kana nearly kills him, but Mariko restrains him under Toranaga’s orders. They wash and dress Blackthorne while Pesaro menaces them with pistols. First Mate Santiago, having overheard the cabin deal, rushes to warn Pilot Rodrigues.

To foil Ferriera, Rodrigues abruptly throws Blackthorne overboard to shock him sober, then has the longboat haul him out and deliver him to the galley. Mariko protests, but Rodrigues claims friendship and a life-debt. Ferriera’s plan to keep—or lose—Blackthorne is disrupted, and the priests prepare to go ashore to placate Ishido while the frigate runs for sea.

Toranaga weighs the advantage of letting Blackthorne’s fate be decided at sea. As the galley beats drums and rows off, Toranaga’s pennant is struck, signaling he is not aboard. Ferriera orders sail for Yedo and grape loaded; the priests depart to manage Ishido. Toranaga remains on deck, choosing not to intervene as the galley heads for open water.