Shogun describes the period just before the establishment of the Tokugawa shogunate. This article describes the system that developed after that, under the Shoguns.

And an even better book, which is a part of an excellent series spanning centuries and Singapore, Hong Kong, Iran, and many other places.

https://en.wikipedia.org/wiki/Asian_Saga

Yes, if you enjoyed the show, I cannot recommend the book enough

Loved that show. There is a fairly recent "Last Samurai Standing" fictional series that portrays the desperation of the Samurai after the end of the Edo era. It's a bit Squid Game-ish, but I enjoyed it immensely.