Tokunoshima is located a little north of Okinawa, part of the Amami island chain. During the US occupation of the Japanese island Okinawa (which continued until 1972!) Tokunoshima was the southernmost point a Japanese tourist could get to without a passport.
If you transferred this scenario to the US, it would mean people from NJ who wanted to escape the snow and go to Florida would need to apply for a passport and a visa first. What would you do to have a nice vacation without the hassle? Probably go to the islands off the Carolinas instead. And that's how Tokunoshima came to enjoy a teeny bit of tourist prosperity.
