Sure they can be leader in the crypto currency if they kept the new additions to its use and development. Like they posted above GMO telecommunication to invest money from he Japan which means more power to acquire the bitcoin in first place of Japan. Currently China is out of the race and hence their crypto market is completely shut which mean any coins over their network is now available for others and mostly Japan would be the one to get it first.

If we measure the leadership in terms of use and possession then yes Japan might be the one soon.