Stupid trivia (Spoiler warning, I guess): If you somehow run out of time in Yuyuko's Boss Battle, Yuyuko will get furious and start vandalizing the izakaya again, and this CG plays, but Kyouko wasn't there all the time, where did she even come from?
A product of a brief golden age, the Machine Intelligence originated in a planet-spanning Servitor system that outlasted the decadent civilization it was created to serve.
I believe the girl is nayuta, but I had a heck of time figuring out who that is, and I'm still not sure how to tag it.
The commentary says there was a real world meetup held to celebrate her birthday on 9/27. Her fans have their own name ("Nayufans") and mascot representation (the winged catball near her head), things I associate with vtubers. But no, no youtube or twitch links. Then I found this tumblr page for her 2023 birthday event: https://nayuta-2023-live.tumblr.com/
It appears to give a set list of 17 songs, most of which nayuta is credited as writing the words, music or both. The poster also implies that she is going to be singing herself.
So it seems like she's a singer-songwriter who borrows from the vtuber toolkit, in that she exclusively appears online as an illustrated anime girl persona. And she has a not-insignificant idol-like fanbase. And she has been doing this for 17 years (long before vtubers even existed).
