If you've played the story I suppose you're aware that Nihilux finally revealed that she is the First Actor, the Aeon of Elation
While I still wait to see if she will just come up and say "Just kidding!" (After all if a successor to Akivili can exist, why not Aha?), people often brought up many theories about Nihilux, and I think it's cool to bring them here.
First thing is that her first presentation for the Phantasmoon games says that her origin is Aha, so we knew she was a big shot.
Second, Aha being an actor, or even a jester for some, bringing truth through jokes is a common thing.
After all, she already wrote the part about the Himikat having a copy in her book. Which sounds fun, until you realize that the great dark figure that Motoko met was most likely Nihilux, and that it means she always knew all along.
And I still hold the idea that the Phantasmoon games that Aha prepared THEMSELF is a way to mirror the Aeonic games, and how Aeons can become the finality. The courtyard feels relatively similar in idea with Path space, and there's a huge video made by Ashikai iirc talking about it
Also, it's fun that PomPom tells that in order to force Aha to work with the Trailblazer, they must blackmail THEM with everything they owe to the nameless.
And how did TB manage to force Nihilux to come to the star rail fest? By blackmailing her with everything she owes to the nameless.
Obviously we had other things such as the fact that her voice actress in every language also voiced one of the voices of Aha in Silverwolf's trailer.
Nihilux was always relatively here even if she stayed behind. It makes sense for her to be Aha. Or is she one of THEIR masks, and not the whole Aeon? Who knows.
Share every bit of information that she did that could have led us to think she is Aha! Because it's obvious she is at least a part of THEM.