well.. another example of why its too easy to get on the Internet - they really pulled that one out of their nether regions
I've never seen any reference to a any law/regulation concerning that for individuals and if you think about it, it fails to even make sense from a trade or enforcement standpoint.
Can you imagine the logistics of trying to enforce such an absurd rule? The border people can't even get enough funding to inspect more than a small percentage of huge tanker shipments much less individual parcels from Japan. And then they'd have to know you'd ordered the same thing previously --- it makes my head hurt just thinking about it.
From a trade standpoint, there isn't any rationale for such a restriction. You're ordering from overseas because no one bothers to carry it locally.
Order away! (wanders off to order fourth copy of the ZONE collection for a gift to a friend).