I do have a question.

Old Man Anjin had Marikos cross. How did he get it after he threw it in the water. I presume it’s a different one?
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I think that was Blackthorne imagining what it would be like if he left Japan to go back to England. He doesn't fully commit to staying in Japan until he tries to commit Seppaku and Toranaga stops him.
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At least they brought the 'Unless I win' back around. It is more subtle in the show but in the book it is made quite clear that is when Toranaga realizes that Blackthorne understands him better than many of his vassals.

In real life Adams and Tokugawa had a meeting that lasted a whole day past midnight as Tokugawa was very curious about Adams' knowledge of sailing and shipbuilding.
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Yes, I took that to mean his potential future if he left Japan after Mariko’s death and lived a life full of regret holding onto her/the past.
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