I thought this was pretty interesting http://www.techcrunch.com/2008/03/15/japanese-isps-to-ban-file-sharers/
how hard they try, they will never success on banning it. millions of users using p2p sharing, how they can block each of them?
There is a few large Japanese ISPs on the market, it just take the few to coordinate and block the ports or the sites and basically most of Japan would be block, it is not unlike in USA where there are thousands of ISPs, that would be difficult to achieve.
My uk friend started the p2p download of a new game, and got email from his ISP, and they have blocked his download. I don't know what the game was. Provider was Comcast, but i might be wrong.
The Web is just a enourm place to go hiding wherever there's a need. Don't know if they can shout down file sharers.