OsmAnd is an OpenStreetMap-based map app. For Japan localities that don't have a name:en= parameter it displays junicode transliterations which are always wrong. rrobek has created an improved map that uses a better transliteration algorithm. But rather than using general-purpose transliteration, using a database of translated place names would be the best.
I am looking for a database that tells me how Japanese places/shops/houses names are usually written in English:
日本 → Japan 原野ビル → Harano building ニセコバックパッカー アスパラロッジ → Niseko Backpacker Aspara Lodge 鉄砲町停留場 → Teppocho station 吾妻古墳 → Azuma tumulus ミニヨン南堀江駐車場 → Miniyon Minamihorie parking lot 藍場浜公園 → Aibahama Park ふじ鮨 ニセコ店 → Fujizushi Niseko
Ideally the license should be compatible with OpenStreetMap, but databases with more restrictive licenses are OK too.
I am aware that no database is perfect, for instance 大分村 translates as Daibu or Oita depending on the prefecture. The database should provide the most common (or even better provide the translation depending on approximate latitude/longitude, but I guess it is too much to ask for).