The following is map of Halal food restaurant/store in Japan. Please note some of those restaurants/stores are not provide halal foods only, so be careful. If you have information about halal (ハラル) restaurant/stores not listed in the maps, please inform me. Also, if you find inappropriate information listed in the map, please inform me too.
The actual url for that Halal Japan map is here,
https://mapsengine.google.com/map/edit?mid=zx_D9Dzdw7Pw.k7mUcrEpPSOg