It's the number you may expect to see in the most contaminated area inside Fukushima Prefecture, like Namie-machi, which is a focus of Asahi Shinbun's "Trap of Prometheus".
But no, this is in Chiba Prefecture, and Kashiwa City is just outside of Tokyo.
Yomiuri Shinbun (11/28/2011) reports:
Regarding the localized high radiation spot in the city-owned land in Kashiwa City in Chiba Prefecture, the Ministry of the Environment announced on November 28 that the maximum 450,000 becquerels/kg of radioactive cesium was detected in the soil 5 to 10 centimeters deep from the surface.
The survey was conducted on November 1 and 2. The Ministry says it is highly likely that the radioactive materials released from the Fukushima I Nuclear Plant accident have accumulated. The rainwater containing radioactive cesium seeped through the broken side wall of the drain, and increased the density of radioactive materials. The Ministry plans to conduct additional survey, and estimate the size of the contaminated area.
In the October survey by Kashiwa City of the nearby location, maximum 270,000 becquerels/kg of radioactive cesium was detected from the soil.
Information about 276,000 becquerels/kg soil in Kashiwa City is in my post here.
Kashiwa City has the details in Word file, on this page (2nd and 3rd files from the document list in the middle of the page). They still only measure cesium-134 and cesium-137. No strontium 89/90, no plutonium or other nuclides such as silver-110m which is increasingly being detected in spider, cow, and abalone.
Natural concentration does wonders, turning Kashiwa and potentially anywhere in Kanto or Tohoku into the evacuation zone-level contamination. Unlike Fukushima's evacuation zone where the national government has said (at least) they will be responsible for the "decontamination", people are on their own cleaning up the radioactive mess elsewhere.