[polm23]

Besides the method skissane mentioned, if you have sufficient capital (roughly five million yen / 50kUSD last I checked) you can get a "business operator" visa, open a business, and have your foreign employer pay into the business. If the "business" runs a profit you should be able to get your visa renewed continually. It's a little more legally complicated to set up, but has advantages like not requiring a college degree or ten years of proven experience in one profession.

I was considering that route to self-employment before I learned about the change in the HSFP visa.

> (I'd even be willing to pay taxes in Japan!)

If you are a resident of a country it's only reasonable to expect you to pay taxes there...