Thank you to NetGalley and the publisher for this ARC!
I did not read the previous works in this series, but there was a synopsis, and I feel like this novel works pretty alright even as a standalone, too, if you can ignore all the dead guys he mentions. While you will definitely lack context, you can figure out the general plot pretty quickly, within the first 20% or so of the book I felt like I more or less got it.
One thing I found SO annoying when reading was his "use" of Japanese - inconsistent, unnecessary, and frequently just seeming very pretentious. So he regularly adds the honorifics for certain characters (e.g. Masugu-san or Mieko-sensei - keep in mind that they should be added to the family name, not the given name, but he doesn't seem aware of that), but does not add them for people of higher rank, such as Hachihime (who should be Hachihime-SAMA by his logic, if he were consistent). He translates place names, completely disorienting the reader and ignoring the fact that, while yes, they TECHNICALLY have meanings, people don't actually think of them as meaning a specific thing any more than Americans think of their home as the continent of Mr. Amerigo Vespucci's land, or people think of Austria as "the Empire of the East", or Chinese people think of Nanjing as the Southern City and Beijing as the Northern City when using these names in everyday speech. It seems very pretentious, especially as the author does not even speak Japanese, and it feels like, through his choice to literally translate the names, he is attempting to exoticise his Japanese setting even further, as his audience is probably familiar enough with Japan to think of names like Edo as perfectly normal (which they ARE).
While he motivates his choice to translate place names with "well, to Japanese people, these place names HAVE MEANING and they KNOW this meaning when they talk about the place", the same is - intriguingly enough - not done for people's given names, which very frequently have much more meaning to any given individual than the city of Edo (Estuary, as he chooses to call it) would have.
Also, if you need TEN PAGES (in my ebook version) of glossaries and place names (not counting the several pages of CHARACTERS), I fear you are just unnecessarily complicating things for your reader. I appreciate the thoroughness with which things such as a katana, kimchi (here spelled kimchee), or honorific suffixes such as -san and -sama were explained, however, was this really necessary? How likely do you think it is that the average reader will remember ALL of this 150 pages in, when the items are glossarised at the very beginning of the book? I feel like this could have been done in a much better and more accessible (and less pretentious!) way. You don't need to hit me with Japanese terms every two pages to remind me that we are in Japan (and you definitely wouldn't if you hadn't changed all the place names from their Japanese original to a whimsical little translation!).
It's also quite odd how he insists on using baka at random times - there's baka lords and baka farms, and it just sounds very childish, in my opinion; like a 14-year-old who just discovered anime and now uses random phrases whenever they can. Giving massive "just according to keikaku (keikaku means plan)" vibes. Add to that that "yes" is, at some times, apparently not exotic enough and one needs instead to say "hai", and it made reading this novel a fairly annoying experience, actually. Especially as, again, the author doesn't even speak Japanese! (Which became very obvious with "I'll help you down, anata" - that really is not how you use anata...)
As well as the frequent baka-ing, there was also a lot of "poop" and "poopy" expletives, which, considering there are people being slaughtered in this novel, felt really quite immature, as well. (I quote: "Then why do you want to go through with [this]?" [...] "So that I can slice the poop's throat [...]." [...] "Serve the baka right." Like, what IS this??)
The writing style itself was also fairly inconsistent - at times, it was all fancy old-timey style, really trying to get you into the historical settings, and other times it sounded like the average YA teenager POV. Each of these styles has its merits, but mixing them randomly didn't work very well, for me personally at least. I think this novel would need a LOT of editing before I would recommend it to anyone, based on the writing style.
The plot itself was alright, but the fact that I was basically goraning in frustration at the writing style every other paragraph made it very difficult to enjoy this novel.