Alright, just spitballing here, but how about:

~ Lucis has 13 moons, each corresponding to a zodiac sign.
~ There are different kinds of afterlives for different species/cultures, each with their own designated guide (Valkyrie, Dullahan, Shinigami etc.)
~ Attempts to map the Black Gale have all failed
~ Earth's moon hosts only abandoned colonies
~ There is at least one Ancient Egypt-esque lost civilization in Lucis