Adding onto the last ask with Ilia and the multiverse. Ilia (by existing) does connect universes and its inhabitants, but those who are not in their OG worlds will not cross paths with the “Main Characters” and hence the plot.
(IE: maybe Peni does exist in the JJK canon world but kit will not become relevant in the plot. Just existing, and maybe dying since this is JJK)
(Just putting this idea out there because I like the idea that they are just NPCs who have zero relevance.)
Ooh! Okay, see THAT I like!
Like Peni just being one of the humans at Shibuya dressed up and wondering why a random ass wall exploded when the tall albino looked at it for a couple seconds.
Or like Riko being a member of a village that asks for help from Frieren and her party.
Just give them enough significance to justify a possible design, but not enough to have to think of an entirely new plot (one off isolated ideas of what their powers could be is something I am also okay with doing, but I don't want to be trying to fit them into a full story, at least right now at this moment).
