Essentially 'Hikaru' is an eldritch horror that accidentally stumbled into our dimension. He just so happened to show up at the same time the Indoh's were doing their ritual so they were like 'omg it's a sign' but really it was just all serendipity. Because making a 'wish' on eldritch horrors ends in disaster, the village was almost wiped up in the great dying. Then no one did the ritual so wishes stopped and 'Hikaru' just big chilled up in the mountains unwittingly preventing more bad things from happening. Now that he's in the village and with Yoshiki, the portal into his og eldritch horror dimension has gone unchecked.
Hope that helped!
It's 4am and I don't understand a thing said in this chapter, Would anyone be kind enough to elaborate it