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For a while there's slight controversy of RT how and why it's a type of Reality Marble. Mostly because, lets face it, it seems more like a NP like Domus than say Babbage's Steampunk Convention or Nobu's Fire Everywhere Lets Get Naked.
I was reading the new old Case Files, the first part of the atlas one. Haven't had much time to read lately because of school. But I got to the part where they Waver was talking about graves and worlds after death. Mostly a rehash of Babylon for the parts about underworlds; however, the pertinent part for this arc is about graves. And how graves in the ancient times and even now serve as a purgatory or in fact "a man made world after death." The examples were like egyptian tombs and norse tombs and so forth. How the grave itself is a world that the soul stays before leaving for wherever.
So then if a grave can be conceptualized as a microscopic world and ozy's NP is summoning a bunch of temples and tombs, then it makes perfect sense why RT is a RM rather than a Domus thing. That is, its is the world engraved upon this pharaoh's soul for the pharaoh's soul was part of that world.
So now is this something Sakurai and Sanada came up with during Fragments? Or just a happy coincidence that lore happens to fit?