Edit
Romaji are Japanese words written in the Latin alphabet. It is seldom used in media, unless for the purpose of educating in the Japanese language or other special purposes. Sometimes used to explain, expound or guide in Kanji/Kana usage.
For Danbooru purposes, the tag refers to Japanese words written in the Latin alphabet where Japanese characters would normally be expected. Thus character names, trademarks, loanwords, etc. don't warrant the tag, even if technically they contain romanized Japanese text. Any piece of dialogue, however, as well as sound effects and similar elements which would normally be expected to be understood by Japanese speakers, but are for whatever reason rendered romanized, do qualify.
Do not use this tag for Japanese loanwords that have been fully incorporated into English, such as "sushi", "tsunami", or "sumo"; "senpai" and "sensei" are borderline.
See also
The following tags are aliased to this tag: romaji and romanji (learn more).
1