Since the outbreak of the A/H1N1 (swine) flu on May 17th (JST) in Japan, the number of confirmed cases has reportedly risen to 267 according Japanese news sources.
Although mainly centered in the Osaka, Kobe, and general Kansai regions of central Japan, cases are also being reported in a couple students in Tokyo who had recently traveled abroad to New York City.
Although most reported cases in Japan have been mild, Japanese officials around the country are still taking precautionary measures, such as postponing planned school trips to the Kansai area, to help prevent further spreading.
Travelers are advised to take basic precautions, such as wearing masks and washing hands thoroughly.
However, since the outbreak there has been a run on face masks in stores around Japan, and securing your own in country may be very difficult. Please consider bringing your own face masks with you if you are planning on traveling to Japan.
See also: The Japan Times Online