The only exchanges that matter are GDAX, Bitfinex, Gemini and Bitstamp. All foreign trading volumes do contribute somewhat, but they mainly affect their own market. I remember when South Korean exchanges were trading $5000 above western exchanges, which is beyond insane, but the western markets didn't give one single damn. Later on South Korean premiums vanished and became just a few hundred instead of thousands -- this perfectly indicates that continents have different demand standards and don't necessarily steer the other side up or down with it. That's the benefit of having different exchanges all operating different order books. 
Totally agree. We have witness South Korea exchanges at a premium high but it didn't significantly affected the price globally. Although Japan has a huge chunk of trading volumes, I think its not enough to offset the Western exchanges to really bring a dent of the price (positive or negative). The price is going on another minor correction, but I do think that it has nothing to do with the Japanese market though.
I was thinking before that Chinese run the market and that is why news from that region do affects bitcoin in the most negative or positive ways. Japanese also have some influence but I don't think that they control the market as there are many factors that determine price.
Chinese case is different. They are faking the volumes and manipulating the price until PBoC caught them.