Rounded up a 3.5. Going in you need to recognize it's a collection of essays that are only loosely connected. They're written at different times for different audiences, so there can be a mixture of repetition between them, as well as insufficient explanation of references that would be more familiar to a specialist readership.
That being said, the focus on the Imperial Army gives an uncommon lens through which to view some familiar events. I am, perhaps to my discredit, one of the legion of white guys endlessly fascinated by the Second World War. And there are several essays that helped me rethink so many simple conclusions I thought I had. The longest essay is probably the best in this regard as it translates and contextualizes some (then-)recently discovered first-person accounts of the war from Hirohito himself. I also found the collection based on its two essays about enlisted and officer education programs in the peacetime IJA. The enlisted essay was much more systematic while the officer essay was an individual profile.
The topics are a bit scattered, but if this sounds like the kind of niche material you'd like, this will likely have at least a few essays that really engage you. It reads pretty quickly as all but the final essay are 20 pages or fewer.