How do I divorce my Japanese wife living in Japan with my son if she won't give me her address?

You need a lawyer in the state you are currently living, but you may also want to seek out an attorney in Japan, in the area that your Wife and Son live. The problem right now is that you can ask for divorce and be granted that in your current state, but they likely won't have jurisdiction over your Wife or Son, to require certain orders that you need for placement, custody, etc. So you can end the marriage from your current state, but will likely still have to pursue placement and other rights to your Son in Japan, given the length your Wife and Son have lived there, and the lack of them having lived in your current state. Since no one lives in the state you were married in, that state no longer has jurisdiction either, given how long it has been. You do need to work with an attorney given the complications of your situation. Best of luck to you.