i think the most many trader in the world is in the korea as you can see korea has now the biggest stock of bitcoin, though it is too expensive but i know that korea is so smart to trade some coins in the market also they are smart because they just make the bitcoin as a leggal currency
Japan is having more number of trading sites when compare with the others trading in rest of the countries. We know that bitcoin is been accept bitcoin as a legal money few months back. Therefore, they would not be worry about it is illegal in usage.
It seemed to me that even until recently, the Chinese controlled the Bitcoin and its sale. Maybe I'm wrong. But really. What's happening lately, a very huge interest in the crypto currency has grown in Japan. The Japanese made such an excitement that the Japanese government made a step towards creating its own crypto currency. Therefore, yaponiya leads a very good business in the Bitcoin trade.