I guess I’ll add my perspective. To me, Kinzo is basically Jay Gatsby from The Great Gatsby.
Think about it, (spoiling Kinzo’s backstory) both men fought in world destroying wars and are dangerously infatuated with a single woman, both men are insanely rich and made their wealth of dark money, both men are constantly mythologized by others in the sense that people create their own tale of who they think that man might be, (Gatsby was a murderer or a spy or the cousin of Kaiser Wilhelm, Kinzo is either a crazily awesome old man, a doting Grandfather, a completely drunken bastard, or a pitiful old dude).
And both men also seem to even create their own delusions of who they think they are vs the reality of the situation. The only difference is that Gatsby wasn’t completely off his rocker and that Kinzo’s Nick was useless and even gayer.
Also, I think Beatrice might share more than a few similarities with Daisy, but I can’t think of them now.
I also think that Umineko (and maybe Higurashi/Higanbana) could also be compared with Moby Dick in how they both share the themes of how vengeance turns you into a monster, and the dangers of being unable to understand your enemy.
What about Rose Guns Days? Anybody have any thoughts on that?
Edit: I’ve often heard that many people characterize Rose Guns Days as a critical look at Japanese culture, society, and politics, but as I hadn’t read it myself, I wonder how true this statement is.