I think you and the others misread what I wrote (I just reread it, and it seems clear to me, but whatever). A Tor user in Japan's traffic from their computer to the next inside the Tor network cannot be blocked easily.
What I said was that the traffic from the exit nodes to the destination address can be easily blocked. The article was talking about preventing anonymous posts being made to Japanese web forums. If they block traffic from all exit nodes, posts made directly from these exit nodes would be blocked as long as the forum is hosted in Japan.
The solution to this problem is to setup an group of I2P outproxies inside of Japan's networks. It will take some time for Japan to catch up to current technologies, if they're only getting around to targeting Tor as late as now.
Also, is Japan trying to copy China, or something?
They can still block any traffic from the exit nodes. All the ISPs in Japan can null route all traffic from Tor exit node IP addresses. The list of addresses is published by Tor so people can do just this (it's not meant for the ISP level, rather, they publish it so people can block Tor from message boards and such). This would prevent all Tor traffic from entering Japan's networks directly
Using a proxy immediately after Tor would be the only solution to this, but even this could be blocked since lists of public open proxies are maintained in a number of locations such as XRoxy.