Mieruko-chan

[Ryllharu]

The big ones that only Miko can see seem to be.

Yulia sees the nicer ones that would fall in with the old lady's husband. Miko doesn't panic about those and they usually don't ask her if she can see them. The ones who ask her repeatedly fall into the category of Japanese ghost horror stories and follow all those tropes like Kuchisake-onna or Aka Manto conversations.

The exes and bakeneko seem to be what happens to someone who can't see them. Hanging around very close to notice any moment of weakness. If either of those three could, they'd be very, very dead. And Yulia starting to see the big one as she began passing out may have some connection? Like the triggers to start seeing ghosts in The Frighteners (or countless anime/manga who do the same "near death now I see ghosts!" thing).

Though lore wise, Miko just started randomly seeing them.