I've got a question: Why?
Why has Japan decided to legalize bitcoin now? I've heard about "it's is good for innovation", "the will to lead the bitcoin economy" etc... but this seems to me quite peculiar for a government not very renowned for its audacious moves (the quantitative easing as everybody, the explosion of the debt etc...).
Or maybe they are in so dire straits, the Yen is about to flank in about a moment, they know they will default soon etc... Something seems fishy here.
some people find something fishy in everything so i don't blame you

but as for why now, it has been a very long discussion in Japan and they prolonged it long enough. there have been a lot of demand for bitcoin in that country and as a result there have been a lot of requests to legalize it. and Japan have always been kind of a frontier to any new technology in the world.
you can see the demand by just looking at how many businesses suddenly started in Japan using bitcoin.