Another question about Crypto and taxes in Japan

Hello and regards everyone. I’ve found so much helpful information on this sub already, and some of you guys really seem like you know your stuff. So I want to ask about the ideal way to buy and sell cryptocurrency in Japan. I know that the idea effective tax rate on crypto ranges from 15-55% in this country. This makes it almost not worth it compared to conventional investments. But I also read that crypto is only subject to a flat 20% tax if you are not a permanent resident of Japan. I live here, and I plan on staying here for a long time (wife is Japanese), but I do not have PR. Does that mean I would only be subject to the lower tax rate? Another question, is it recommended to Saigon up for crypto exchanges with my Japanese ID, or my American ID? I know that some exchanges such as coinbase do not operate in Japan, so I could potentially lose all my money if I used it here. Some exchanges however are available for citizens/ residents of both countries. If I used my Japanese ID, does that mean all my crypto gains would be sent to me personally to sort out tax-wise? At the moment, my employer takes care of all my taxes without any input from me. Does that mean it would be forwarded to my employer? Thanks in advance. Question 3: should I use a Japanese or foreign CEX if my money is all back in America in USD?