Don't they have zero trading commissions on many Japanese exchanges? I know Bitflyer.jp had no fees at some point. It might still not, I'm not sure.
I know a couple traders that always always watch the Bitflyer chart. I'd agree with them that Bitflyer leads sometimes, but not often enough that I particularly care. Same goes for Bithumb in Korea. At the end of the day, all charts reflect the same sentiment. Arbitrage (or the expectation of arbitrage) takes care of that.
I think they do which means those volume figures are irrelevant. Bitflyer said it was temporary but it may well still be up there.
Korea should be discounted completely as there's absolutely no way foreign money can access it whatsoever. Like I said I've never seen anyone anywhere mention the JPY price. I'm sure the Japanese do.
Everyone else is looking at the usual Western places.