It's just common look for "voids", "limbos" or "lifeless worlds", i think.
This, mostly!
I *have* watched Death Note, but it was so many years ago that I legit didn't remember there was something like that there! So I'd say, it's not exactly inspired, it's made like that for its own reasons, but it's a somewhat common look, yeah. :)
I'll probably set up something silly like a curious cat on Twitter or something to sometimes answer this type of small question. Either that, or maybe I'll encourage joining the community Discord server for the VN that might be coming soon... ;)