781 strings, machine-made and marked Beta, on the same terms as the
languages before it: the report link stands in for the native speaker we
do not have, and a missing entry falls back to English.
Plurals: there are none. Intl.PluralRules("ja") returns `other` for every
number, so each counted string carries one form. Counters do the work a
plural would — 通 for messages, 件 for conversations and items — which is
why "{n} messages" and "{n} conversations" are separate entries rather
than one pattern. The number alone does not decide the word after it.
Register is です・ます throughout, with the pronoun dropped: where English
says "your mailbox" this file usually just says メールボックス. Buttons
are the bare noun or verb stem — 送信, 返信, 削除 — not a sentence, which
is what every other mail client the reader has used does.
Script mixing is deliberate. Kanji for the noun carrying the meaning,
katakana for the loanword the reader already knows (メール, フォルダー,
アーカイブ), hiragana between them. Long vowels keep their ー.
Verified against the mock server: role folders localise and custom ones
are untouched, dates follow the language, and "{used} of {total}" comes
out reordered as "2.0 GB 中 700 MB" rather than word-for-word.