"The Fifth Profession" by David Morrell is an intriguing tale of two bodyguards stuck with "false memories". They both believe they saw something traumatic, but find that item after item in their recollections did not actually happen. I've run a feudal Japan newsletter for over 10 years, so my main interest in this story was with the Japanese samurai tradition covered, as well as the bodyguard ethics.
The main teller of the story is American, but his counterpart is Japanese, and there are many interesting aspects to his personality and background. Part of the story takes place in Japan, in various areas of both city and country. The bodyguard was trained by a skilled ninja-type (of course) and the descriptions of their fighting style are also intriguing.
The narrative examines the background of Japan as the plot wends its way here and there. Readers learn various stories such as the 47 ronin, and backgrounds of the tea ceremony, zen gardening, bushido, and more.
While this book is not really meant to teach about Japan, the writer did a good job of researching his topic and slips much of the information in as casual background to the story.
If you can accept some of the plot holes at the end of the story, and don't worry very much about details that do not quite match up, this is a very enjoyable book!