Basically they probably can be affected with guns or physical means.

In retrospect I guess I underestimated the time it takes for an exorcist to arrive. Also I don’t think Everly can really fight against pure supernatural/ghost creatures unless they are pretty weak with her items so I assume they are like a guy with special abilities.

The exorcist would need to be contacted, arrive, and kill off the Undertaker within the probably 16 hours before the next day. That’s not a lot of time…
We know it’s a one day timeloop, or at least, he has never survived to see the next day.

Makes sense though I feel like Orff could call an exorcist if so, he seems wealthy enough. And if an exorcist can’t solve the issue Everly can’t beat the Undertaker so… I mean they could spend a lot of money but also how could it take another 11 chapters to solve the arc(if the Undertaker is supernatural), 9 if it takes two chapters to convey info, if in Situation A: They call an exorcist to beat what Everly can’t or Situation B:They call a Wester level exorcist who beats the creature. I guess situation C: Everly needs to help the exorcist could stretch the arc but by 9-11 chapters? Or situation D: where exorcists can’t arrive in time but it doesn’t seem too plausible they can’t hold off long enough for an exorcist.