My reread of
Shibumi (1979) by the author who wrote under the pen name of Trevanian. A compelling story with rich characters in the spy genre, that jumps back and forth from WWII Japan to the then present 1970s. The author, an American through his characters offers some distain for Western cultural values, but imo, it fits in nicely with the narrative, and perspective of the lead character.
My only critique is that the story tension builds to what might be anticipated to be a tremendous climax, but is somewhat of an anti-climax although it is reasonable and works.
The title refers to a Japanese word which descrines a particular aesthetic of simple, subtle, and unobtrusive beauty.