I've mentioned this one before, but really if you need to see the very weirdest from Japan this has got to be on your list. Not for the faint of heart mind you the film starts with eighties school girls cheerfully jumping in front of a speeding train. I can't think of a more bloody beginning of a film.
The film then gears into the strange. The police find two bags. The first bag contains skin of the people who have committed suicide. The second constains skin of those who haven't yet. There's a website that charts who has died. There are hackers and creeps who are trying to figure out the mystery on their own. The Police are freaked out and confused and by this point of the film even a musical interlude doesn't seem too far afield.
I can't say I understand this film, but I can say it engrossed me. Certainly, if you are a horror fan, or a fan Japanese film you have to watch this.