An English pilot is shipwrecked in Japan in 1600 and spends eleven hundred pages failing to understand where he is, which is the structure doing its job.
The point of view keeps shifting away from him to the Japanese characters, so the reader gets information he never does, and most of the tension comes from watching him misread rooms the reader can see clearly.
Toranaga is the actual protagonist. Blackthorne is a piece being moved.
Read September 2021.