Probably China. They are the biggest player of bitcoin for many years. I think they are also the biggest bitcoin miner as far i know. The next i think US but there are problems regarding on the legalization of bitcoin there. Maybe Japan can surpass US or even China due to massive adoption of bitcoin there. Many establishments there are now accepting bitcoin. Bitcoin growth there is phenomenal.
Japan is a very promising country for trading bitcoin. In addition, the currency has been legally legalized there, and the profit from its activities is taxed by a minimum eight percent tax. All this reduces the possibility of fraud with crypto currency. In Japan, there are 260,000 points trading for crypto currency and the possibility of its use there is constantly expanding.
You'd better look at the statistics of Bitcoin implementation and the transition of Japanese citizens to the legal market of crypto-currencies. What the mass media say, and does not mean anything, and since the crypto currency is an anonymous means of obtaining financial benefits, a person will use this moment for himself. To date, no legal support is needed for Bitcoin, as there are no levers of influence on this business.