When the news first broke, the meat was supposed to have been sold in only several prefectures; then 8 then 10, now 26 and counting.
People, from Mayor of Yokohama City on down, say "We thought it was safe because it was being sold in the market."
According to NHK's Kabun (Science and Culture) Blog's tweet, the prefectures are:
Tokyo, Chiba, Kanagawa, Saitama, Gunma, Tochigi, Ibaraki, Niigata, Nagano, Miyagi, Yamagata, Iwate, Akita, Fukushima, Aichi, Ishikawa, Fukui, Yamanashi, Shizuoka, Osaka, Kyoto, Mie, Hyogo, Ehime, Kagawa, Fukuoka.
The only prefectures in the eastern half of Japan that haven't been found with the contaminated beef are: Toyama, Aomori, Hokkaido
The Japanese people who are against nuclear power plants had better start demonstrating against radioactive food and radioactive garbage, among other things, that have been forced on them through the government action (like raising the safety limit for radioactive garbage ashes) and non-action (like not testing rice hay for radiation). They may get their wish of nuke-free Japan, but unless they start to fight the small details right now, the nuke-free Japan may become inhabitable.