Bitflyer surprisingly could pass the regulations in the US as there are just a few exchanges could survive in there, even Bitfinex has pulled out their service from the retail marketplace in the US. But, people in the US have to report their capital gains if dealing with exchanges, to ensure there is no one that doesn't pay taxes, exchanges have to reveal their customer's id to IRS and every transaction they've made. Then, why Bitflyer dare to be involved in the US market? Because US traders and investors seem to like the biggest players compare to other countries;
bitFlyer primarily target institutional investors who make an “untapped” market. The marketplace and platform are designed for professional traders who routinely trade $100,000 or more in cryptocurrencies each month, according to the exchange.