English. Optional. The word as translated into English. Note that this will sometimes be the actual Japanese word due to it being adopted into English.
kanji/kana. Required. The word as written in Japanese (kanji, kana, Roman letters, and possibly other marks).
rōmaji. Optional. Transliteration of the Japanese word, using Hepburn Romanization.
lead=yes. Optional. This should be used for the first instance of Japanese, usually in the lead. It gives the reader an idea what kind of non-English writing they are viewing.
extra. Optional. Can be used to add a gloss (particularly if there is no English form). Can also be expressed as a named parameter, extra=
extra2. Optional. Can also be expressed as a named parameter, extra2=. It is only useful in ";" definitions (extra2 will be displayed without bold, whereas text following the template will get the bold).