Hi RS,
I wish I could help, but I'm not sure anyone would be able to ship to Florida! In the case of Canada, it's relatively easy to show people the CFIA ARS system (like the USDA's ACIR system) which shows there's no requirements on import for fruit. I've mostly been dealing with a growers through a friend who's in the industry, but I've had luck with one or two other places on my own. Looking at ACIR, it looks like you need a permit, can only bring in Citrus unshiu, it must be a commercial shipment, and must be from specific islands. It may be that some regions within Japan are subject to additional requirements I'm not encountering, too.