Jim,
I had the opportunity to do some hunting on the east coast of Japan a few years ago. The beaches were virtually all un-hunted as I was there in the dead of winter and found stuff everywhere. This was the only place I found several platinum pieces in a 3 day period!
When I asked some of the people I was working with (unrelated to treasure hunting) about hunting some of the land sites I saw with the history that was evident, the response was overwhelming COLD! The Prefectures (counties) have a strong sense of history and protect it with a passion. Before you hunt ANYWHERE other than a beach, I would make sure that you check to see what restrictions you may run up against in your area.
A suggestion I might make is to touch base with each of the manufacturers and ask if they have a dealer in Japan especially near where you will be moving. Contact them and ask if they know what additional restrictions might exist. I know that Garrett Electronics & Fisher Research have a distributor in Japan which would be a start.
Hope this helps.
Andy Sabisch
