Nah It's more like Mars new world order than Demon new world order as Lavinha has more than one time has expressed to genocide the whole demon race and hellele was also excited and encouraging mars to purge the weakened demon race.
It is also evident that the cult is called mars cult than demon cult and both demon king and the hero are effeminate and are being cucked by mars
Ceci is getting hotter and hotter as the game progresses. Truly the best girl
Well the game obviously has different routes, but we cannot ignore the importance Nitro has given to the race war:
Cecille was forced to call Mars "demon" before the reveal, because she has a "romantic" fantasy of basically letting the world end by going away with a demon. Also Cecille changing her opinion on demons and instantly saying "all hail demon-kind", after being by far the most racist and genocidal character I've ever seen in a VN (maybe I lack the experience lol).
Lavinia is different because she is an agent of chaos, in this case I 100% agree it's a "cuck em all" and she's the most Mars-centered because she doesn't want to join either side.
Sera is the opposite but kind of the same on a practical level, still 95% Mars-centered but with race still being relevant, and since she's an outcast like Mars we get different portrayals compared to the rest.
Elena is the real issue here, she basically betrayed human-kind over and over again in the most brutal manner possible, she's becoming both Mars' biological and adoptive mother but in a context that makes everything hurt 100 times more. She is the one who actually embodies the DNWO fetish WHILE still managing to give most focus on Mars (but we simply cannot ignore all the jewel/sect events and other dialogues, it's way too explicit about the fetish being portrayed).
Erin represents the race fetish not in a direct way. He becomes the classic cuck who changes genders but in a different social context. Everytime he loses something it's a win for demon-kind and we have a lot of scenes of him being humiliated by the girls acting like they're demons.
Every route adds a bit of nuance in order to feed this fetish, but obviously Netori remains to be the main genre of the game.
I believe I've read somewhere that when in the future Nitro fully emphasizes this kink in some route, it will be a dead end because that's not what Mars actually wants (he seems to be aware that reverse genocide is inevitable if we follow Elena's methods and wants to advocate for peace) and most probably something the Goddess won't accept.
So yes it's a Mars new world order but we cannot ignore the connotations, Nitro has been supporting himself on this fetish and its ramifications. Basically because it's an extremely effective way of displaying cuckoldism/humiliation fetishes.