I'm guessing it's this from the "usable for MH4 and Pokemon X/Y" tags. Did you use a JPN VPN or did it work out of the box for you?
That is the one. Mine will be here in a couple of days (it's already in transit.) To my knowledge, the ones that I have seen being used here in the US were able to use out of the box as I've yet to here of any issues (albeit that the number of units in circulation here is still very small.) However, I can't tell you firsthand on that one like I can on the Bank issue.
If I find out something concrete before I get mine and nobody else has posted the answer, I will let you know.