It is not only the Japanese are buying but the other news is about ETF approval this month which is creating the boom market in the bitcoin price. and if it got approved then we can see $2000 price in this month itself.
Don't expect it to be approved because SEC said in their statement that "The commission notes that bitcoin is still in the relatively early stages of its development and that, over time,
regulated bitcoin-related markets of significant size may develop." It was stated on last months SEC decision and from that till today,
regulated bitcoin-related market has not developed that well and it's size for now is not significant compared to those non regulated ones so I think ETF again will be rejected. Because of this reason, I don't think for now at least that ETF will not drive bitcoin up to 2000 US Dollar price.