(Spoilers) A tablespoon of questions, a splash of theory...
Firstly. In regards to the movie: Wow... Amazing film. Easily one of the best Horror movies of all-time IMO. This blend of Eastern and Western religion and myth is a feast for the senses. Now on to some tough questions that have been bugging me.
1) If the village spirit (woman in white) + many theories are to be believed, then the detective had indeed condemned his family by committing the sin of xenophobia (or murder by xenophobia). If that truly was the case, what is the motivation of said spirit when she initially tells him that the Japanese man is out to suck blood? Doesn't that invariable send him down the war path? Remember: at that juncture of the story, the detectives had no leads and were still bumbling around in Fargo-ville trying to wrap their heads around the murders. I'm currently leaning toward the belief that the Japanese stranger was indeed a Tengu (great write-up here:http://www.newworldencyclopedia.org/entry/Tengu). If that was the case, the villagers could've turned him into a demon by reflective escalation. In the historical context, Tengu can be good, bad, or both - but it's usually within the eye of the beholder. When the acolyte tells "it" what is is near the end, the Tengu is free to complete the transformation into a demon, as even the only man who tried to treat him fairly has abandoned him along with his god. This would explain why he breaks down into tears a few scenes before his final transformation. While he definitely wasn't a force of good, bad things seemed to happen only after the rumors started of his evil. I mean, he lightning bolts a dude for Christs-sake. If the rumors/visions that appear are true or not is rightfully never explained. The village spirit was obviously manipulating the people into thinking a certain way, so why would it be her followers' fault if they "took the bait," so to speak? My only other though relies on the Tengu mythos applied directly to the village spirit. This would mean that the collective psyche of the town distrusts the Japanese stranger and is likewise reflected in her as well. Which leads to...
2) Why is the village spirit always talking about her grandma? And what/who are the two photos of at the Japanese stranger's shrine? Is there a potential link to the past between both that was not presented in the story? It would be feasible, given a mortal's inability to deal with forces like the supernatural when their only weapon would seem to be belief. And finally...
3) Why was the Shaman hinted at being connected to Japan? It's been pointed out that he drives on the left side of the road, commits sacrilegious acts, wears Nihon undergarments, etc. I have the hardest time buying any connection between the two since no concrete evidence is ever given (a strong theme in the film). When both Shaman conduct their rituals, the director admits to staging it ambiguously so that you don't know who (or what) is actually being effected by either. But if so, what's even the point of creating the zombie? Or causing a death hex on your rival/possible teacher? So seriously, is the Japanese connection more than just a filmmaker's metaphor?