It's "Koshihikari" brand rice, but since it's not from Niigata the rice may be blended and sold. If it's blended, there is no requirement to state where the rice was harvested.
Caveat emptor, except the buyers don't have all information available to them to decide on their own.
From Sankei Shinbun (8/27/2011):
千葉県は２７日、市川市で栽培された収穫後のコメの本検査で、国の暫定基準値（１キログラム当たり５００ベクレル）を大幅に下回る４６ベクレルの放射性セシウムを検出したと発表した。「健康に問題ないレベル」として、同日以降の出荷を認めた。
Chiba Prefecture announced on August 27 that 46 becquerels/kg of radioactive cesium was detected from the rice harvested in Ichikawa City. The prefectural government considers the level as "not affecting health", and has permitted the shipment of the rice as of August 27.
東京電力福島第１原発の事故後、千葉県では白井市の収穫前のコメから微量のセシウムを検出しており、今回で２例目。全国では茨城県鉾田市、福島県二本松市に続いて４例目となった。
In Chiba Prefecture, a small amount of radioactive cesium was detected in the rice before the harvest in Shirai City. The detection of radioactive cesium in rice in Ishikawa City is the second in Chiba, the fourth in Japan. One location in Hokota City in Ibaraki Prefecture and one location in Nihonmatsu City in Fukushima Prefecture also had radioactive cesium in rice.
千葉県によると、セシウムが検出されたのは、２４日に市川市の１カ所で採取したコシヒカリの玄米。千葉や野田、成田、銚子、旭の５市のコメからは検出されなかった。
According to Chiba Prefecture, radioactive cesium was detected from the brown rice of Koshihikari taken on August 24 in one location in Ichikawa City. No radioactive cesium was detected in rice in Chiba City, Noda City, Narita City, Choshi City and Asahi City.
千葉県では、これで本検査を終えて基準値以下だった４２市町村でコメの流通が可能になった。
Rice can be sold and shipped in 42 municipalities in Chiba Prefecture now that the post-harvest testing has been complete and the level of radioactive cesium was below the provisional safety limit.
That's what the provisional "safety" limit is there for: to plant the idea in people's mind that anything below that limit is "safe". Clearly many producers and all of government bureaucrats from municipal level upward believe that, and excoriate consumers who still don't buy that argument (and don't buy the produce).