Guess I could add a post about what's not in the setting book for those who are curious.
There are no tables of goods and prices. Theres an extensive section on Trade within the empire, but its setting material, not mechanics and numbers.
There are no new schools specific to any of the seven great clans. Yes, the kitsune spirit and kolat saboteur choose a clan and family, but there's no "Scorpion Bushi" for example.
Theres no premade adventure in this book. Like the core rulebook, it's purely rules and information cover to cover. Seems like they're keeping the progression of "Beginners box, free DLC, GM Kit, then Mask of the Oni"
Theres no expanded explanation for how range bands should work in play.
Theres mention of the other races... tengu, kitsu, ningyo, trolls, zokujin, and naga. But that's about it. I assume there will be an ancient races book down the line to probably tie in with an adventure book that encounters one or more of them.
Again, this book is just over 250 pages of "how does Rokugan function?" And anyone who's been asked by a player about Rokugan's structure, logistics, specific locations, or even what's still canon and what's not will find this book an absolute gold mine.
My only gripe is that because every few pages theres a block about rumors for the area or the sketched out plots, I wouldn't feel comfortable lending the book to my players to peruse on their own like an encyclopedia.