the area code is: JAXX0099 for yokohoma, Japan
in XBMC go to settings > weather > then type in the code: JAXX0099 once you have clicked on the search button.
to find the code go to weather.com > click on world at the top > type in the country you want to find > select the city you want weather from.
the weather code will be displayed in the URL in your browser
code for Fukushima, Japan
hope that helps. if you really want i might be able to do a tutorial on it if it really matters.