I'm honestly surprised at how much Imu talks this chapter.
The fact that they refer to themselves as "Mu" (Which means void or dream...while also being the name of a old Atlantis-like lost continent) is making me think I was right, and Imu IS a woman. Talking about yourself in the third person isn't EXCLUSIVELY a female thing in Japan, but I feel like it comes up more often with female characters, as it's a way to make them slightly more "cute". And even though her gender is still technically unclear, this chapter DOES seem to confirm that Imu is 800 years old, at least. She seems to have too much personal knowledge about the Void Century otherwise.
Also this means that the "Void Century" and the "Empty Throne"...COULD be called "Imu's Century" and "Imu's Throne". Clever.
Given her attitude and personality...I'm kind of getting a "eternal child" vibe from her. I wonder if she's actually going to turn out to be a Immortal Child-Empress. Which would KIND of make sense with how the Celestial Dragons act. Maybe the Celestial Dragons were all her old playmates back when they were all children...but she's the only one who never grew up.
We only really get bread crumbs this chapter. They tease at what the "D" means. It's probably "Dawn", but they still don't spell it out. But, the idea that Lili was the one who spread the Poneglyphs around the world is a interesting piece of world building.
But, the thing I REALLY want to talk about are the Gorosei's Devil Fruits. Yes....the Gorosei seem to have Devil Fruit powers. Either that, or Imu's power somehow cloaks all her allies in shadow, because the artwork is really hard to make out. Clearly, Oda wants to tease these out a little more. But, I kind of want to speculate on what they could actually be. I'm going to assume there's some sort of theme with the Gorosei's Devil Fruits...but they COULD just be 5 random super-powerful Fruits. (It's not like CP0 or Blackbeard's crew really have themes for their Fruits) But, it's more fun for me to speculate about a possible theme that could link all of them. I'm thinking these are all Mythical Zoan Fruits of some kind. We even see the "sash" that denotes a awakened Zoan around a few of their necks. Their bodies change too much for them to be other types of Fruit, I think. Except for maybe the "Human".
They're all hard to make out, but we see: A Bird, a Human shape, a Lizard or Frog-like shape, something with Horns, and...something that looks to me like a Boar or Elephant with Tusks. And it seems like Imu is represented by a giant pair of eyes behind these 5 main shapes we see.
Given we also see something that looks like a devil's pointed tail cutting up Cobra this chapter, I have to wonder if they're based on old Demon artwork. Like the work of Louis Le Breton. But, I looked through some examples and I can't find any really great matches. They still COULD be inspired by Demonic artwork, but I'm not seeing a connection, outside of the "tail"...which could just be a "tongue" of a "dart frog" or something. I DO really like the irony of the Gorosei actually being Devils, though.
Then, given my speculation about how these guys COULD be references to Saint Seiya, I wondered if they could be based on different constellations. And that could still fit. I could see the one with "Horns" being Taurus the bull or maybe even Cancer the crab with the "horns" actually being pincers. They can't be 1:1 matches with the main characters of Saint Seiya, because if they were we SHOULD have TWO birds. One for a Phoenix and one for a Swan. Still, given the planet theming (with...ONE of their names so far), I think constellations fit pretty well. The Bird could be Aquila (or Cygnus or Apus), the Human could be Orion (or Perseus or Hercules or maybe even the Southern Cross as a "sword"), and The Frog could be Lacerta.
But, I think the theming that fits the best with the silhouettes we've seen so far is actually yokai. These shadowy, kind of crumbled and weird-looking silhouettes kind of remind me the most of classical yokai artwork. Here's a list of possibilities: Ushi-Oni (Ox-spider), Gashadokuro (giant skeleton), Akashita (Red Tongue), Ogama (frog), Kamaitachi (sickle weasel), Itsumade (bird), Inugami (dog), Mikoshi-nyudo (extending neck), Nue (Monkey-Tiger), Yume no Seirei (Nightmare Old Man), Tsuchigumo (Demon Spider). The "Horns" actually looks a LOT like the artwork for a Ushi-Oni or Tsuchigumo. The Human actually does have a similar look to some human-like yokai like Yume no Seirei or Mikoshi-nyudo. So, I think this maybe matches what we've seen on the page the closest. Them having Mythical Zoan Fruits based on yokai could actually be pretty cool.
So, yeah, not a lot to go on, but speculation is fun.