Earlier quoted context omitted.
Fortunately, I am blessed with friends who have already made the jump, in many different directions, so I have firsthand testimonies of the pros and cons of moving to a variety of different countries. Japan sounds nice.
Unless you're fluent in reading and speaking Japanese, don't move here. It's a nightmare. Pick a country where you know the language. And consider renouncing your citizenship to avoid taxes if you have the prospect of attaining new citizenship.
There are few countries where the taxes are lower than the US Federal ones. Thus though you will have to file a tax return, in most cases you won't owe any additional taxes.
What makes the US more expensive is all the non-tax fees that are included in those foreign countries' taxes (e.g. medical costs). So you still save.
Perspective: not a US citizen through currently living in California.