In works aimed at adult Japanese speakers, furigana may be used on a word written in uncommon kanji; in the mass media, they are generally used on words containing non-Jōyō kanji.
Furigana commonly appear alongside kanji names and their romanizations on signs for railway stations, even if the pronunciation of the kanji is commonly known. Furigana also appear often on maps to show the pronunciation of unusual place names.
In Japan, by law, newspapers using kanji outside the jōyō kanji list must annotate them with furigana.[1]