Where are you seeing Japan as #1 in volume? Looking at
http://data.bitcoinity.org I'm seeing these volumes for the past couple weeks:
| Volume (in BTC) | Week 7/23 | Week 7/16 |
| USD/BTC | 621k | 982k |
| CNY/BTC | 180k | 255k |
| JPY/BTC | 94k | 168k |
Looks like Japan's volume is still way behind both China and the US.
Good information, china has always been the biggest rival for america and japan. In the future China will become a Super Power State, many predict as it is.