According to Ministry of Education, Culture, Sports, Science and Technology, the radiation level (gamma ray) in Tokyo was 0.036 μSv/h before 311. And now with the Japan fukushima nuclear contamination Tokyo 13μSv/h.
13μSv/h is 388 times more than what the Tokyo government measures at Shinjuku, 176 times more than their measurement in Edogawa-ku.
Here is what the Tokyo government finds at their (concrete and metal) monitoring posts (some of which are conveniently located 23 meters above ground):
Radiological Disaster Survey in Tokyo Suburbs: 13μSv/h in Kashiwa, Chiba 2014-08-24
Radiation back ground level was 0.036 μSv/h in Tokyo before 311
Courtesy of Troy Livingstone and Bruce Brinkman