Japan Tourist Maps
This site provides maps of Japan for international tourists. These maps are very detailed (containing most small streets in- and outside of towns, as well as information about bus stops, stores and hotels), have place names in English (or at least in Latin characters), and are fully searchable. They can be used offline: after you have downloaded the maps, no internet connection is required.
The map is divided into nine regions. To download a map, just click on the region(s) that you're interested in.
If necessary, uninstall any standard OsmAnd maps of the region, because they will conflict with the tourist map.
Copy the map file to the Android device. If you have downloaded the map file from this site,
be sure to unzip it first.
Put the map into the osmand data folder (you can check which it is under Settings → General → Misc → Data folder)
Afterwards, you have to change the description language (Configure map → Description language) to English to see the place names in English.
Also, as the base world map has not been created using JapanMapTranslate, you will need to zoom in a bit so that your local map is actually used.
I can't zoom into the map / The map is not recognized
The place names are wrong / sound like chinese
Nara (south-east of Kyoto)
These maps have been created with my program JapanMapTranslate.