[devindotcom]

So I'm guessing this will work on the retailer/exchange side? Any transaction of guaranteed value (i.e. not just shifting wallets, but something like BTC->goods or BTC->cash) will just have a built-in extra cost in JPY equivalent, if the party gaining money is definitely in Japan?

Sounds great to me, though the volume will be very small to begin with. This is a great opportunity for sites and services to demonstrate legitimacy in the eyes of the law and their users. Of course there will be some dark exchanges and the like for those who'd rather not have a tax record attached to their wallet, but for lots of people this will be very beneficial.