Alright I'd be scared shitless too if I see a kid having a dance with shadowy tentacles. Nothing is creepier than the combination of a child + supernatural shit
Yui's inability to use prostheses might be due to inadequate muscle signals. If the muscles and nerves in her legs are completely dead, then control of prosthesis would be impossible
I think the fact that the story goes this far after Shizuko's meddling and she still isn't turned into a pile of ash hints that this time travel involves the good ol' alternate/multiverse concept.
@Koyomiya @Zblurth Yeah I read all of those. My point was immortals / long living people can have mindset that seem somewhat alien to us, and that makes it hard to deal with them. And Frieren is so long living from our (humans) perspective she might as well be immortal anyway. Though in Slime...