So many mysteries.
We know Hana saw the shrine and the son of the old lady did too,so it appears that wasn't a spectre illusion.We see from the ruins in this chapter that there was something there atleast at some point.
Looking back on the chapter they go to the shrine it appears neglected and in disrepair but not to this extent, so I’m thinking some kind of time portal or gateway activated because of miko/Hana powers.
It didn’t activated this time due to the Stone In her pocket given to her by the guy.
But ya I honestly suspecting the guy is up to no good mostly due to his effectiveness and the fact joining up with him would essentially weaken what makes this manga so great.(miko’s constant terror)