The Japanese government won't let Sony turn PSN back on in Japan until it's sure Sony has made it properly secure.
While PSN sputters back to life in other parts of the world, in Sony's home turf of Japan, it will remain offline, at least for the time being. The Japanese government says it needs more information from Sony before it will give the go-ahead to restore the service.
Kazushige Nobutani, Japan's Minister of Economy, Trade and Industry, said his government had met with Sony on the 6th and 13th of May, but that the company had yet to properly answer questions about two key area. The first, Nobutani said, was the preventative measures that Sony outlined in its May 1st press conference. Nobutani said that Sony needed to assure the Japanese government that it was doing everything that it said it would to prevent another breach. The second area was that of customer confidence. Nobutani said that other Japanese companies have had to make amends for lost data in the past, and it wanted to make sure that Sony's plans measured up to the precedent.
While it seems strange that Sony hasn't been able to get things back up and running in its own backyard, the PSN restoration is staggered, so it isn't as if Japan is the only place still waiting to get back online. Sony will almost certainly want to deal with this situation quickly however, as it has an awful lot of customers in Japan.