Politics of the Moon Kingdom

[Labster]

being required to basically put all its construction and trash and whatnot in subduction zones so they'd get wiped out and leave no anomalous artifacts to cause problems for the next sapient species to evolve on Earth.

This makes no sense, and is not how people act.  Yes it could explain it, but I prefer explanations that don't require people to act completely differently than they do in real life.  Like, find me one person who wants to clean up all of our trash so that we can leave a nice planet behind for the AIs.

Although, as I get into nationalism, maybe it is on-topic?  Every nation has to have a national myth.

Heh.  In Desperately Seeking Ranma, the Silver Millennium is the myth.  <grin>

Later incarnations of Sailor Moon have started portraying the moon folk as humanoid alien refugees who settled the moon because the Earth was already inhabited, unlike the earliest versions, where they are humans who somehow "magically" happened to develop and found a civilization on a dead world with no biosphere.  Since we're taking Serenity I's claim to be a goddess literally (and we're explicitly using original anime continuity), then the foundation of the myth would probably be something along the lines of a "chosen people".  Humans obviously couldn't evolve on the moon, so Serenity or a predecessor (serial reincarnation?) must have taken a population from Earth to the moon to be her people  there.  There would certainly be no small amount of arrogance built in, which as the Moon Kingdom grew in power would probably cause problems with diplomacy.  "She chose us, and we grew to fill the system, while you're still stuck on your one planet."  (And if the Kingdom's rise from "small colony" to "interplanetary power" happened fast enough, there would certainly be resentment on the part of the Earthbound nation or nations, which ties in nicely to the SM backstory.)

Honestly I had already been thinking along those lines: in my Tolkien crossover, they're literally space elves on the Moon.  Well, space half-elves, which are surprisingly a canon thing.  Arrogance comes with the territory

There were lots of chosen people in the past, and each city had its own kami, like Athena for Athens.

The story above does feel like a nationalistic story.  In a feudal society, a royal marriage between Endymion and Usagi Serenity seems like it would solve the problem entirely, especially so because it's a love match.  Resentment is more of a nationalist idea; early conquest is about security and economy, not about whether a Volk deserves more land due to their special destiny.  If Metalia is a stand-in for the forces of modernity, nationalism, and imperialism, then it ties into Tolkien even better, ne?

Since it was a love match, I wonder why they weren't officially betrothed.  Serenity grants it to them in the next life, so she's not against it as a mother, but she may have had political reasons to oppose it at the time.  Is it because they're goofy teenagers?  I mean, we see them do the Romeo and Juliet thing at a balcony, then the masqued ball thing.  Maybe it's Prince Endymion's father preventing it?  But why take the Moon by conquest?  Bella gerant alii, tu felix Austria nube – Let others wage war: thou, happy Austria, marry.

... Yeah, I really do need to make a post here on nationalism.