How can I get Japan Map with English

The "standard" map style on openstreetmap.org uses names that are in use locally for the regions in question. Currently ther is no rendering/map style independent user selectable labelling available on openstreetmap.org, but for example the "Mapquest Open" layer is in English only (note that the future of this specific layer is unclear and I wouldn't depend on it remaining available).

If you just want access to the map for navigating you could give OsmAnd a try on your Android phone.

Go to menu/configure map/map language. That will allow you to choose between Local Language (of the mapped country) and a variety of other languages from a drop down list.

Only ways/POIs etc which have been tagged with name:en=* will display in English - anything not so tagged will still display in the local language. Have a look at this wiki page re name tagging (http://wiki.openstreetmap.org/wiki/Multilingual_names#Japan)

There is also a multilingual map demo at http://mlm.jochentopf.com/ by Jochen Topf

Another map that shows latin characters ("english names") is the OpenStreetMap German Style.

Unfortunately, for many smaller towns and most street names, the OpenStreetMap data doesn't include English (or romanized) names. However, if you use OsmAnd, there are now a few special maps available which add romanized names for almost all places using automatic transliteration. For international tourists who cannot read Japanese kanji, this will make it a lot easier to read the place names and pronounce them.