Seeing as their story is told non-chronologically Inubousaki’s aura could be any number of curses, the Birth-Monk’s Well, whatever the family curse is. We know she eventually gets got, this is just more confirmation that whatever it was was BAD!hmmm, I like that the haunts are shown from their own perspective at first. and the horror they go through not being able to recognize they are the spirits of the dead.
Also super interesting to see that Inubousaki has like ultra rancid occult vibes. Wonder what's up with that.