ex. 区役所 is translated into "Ward Office", "City Hall", and other terms depending on the context. 源泉徴収書 can be translated as "tax withholding statement," "yearly income statement," "Japanese W-2 form," and other terms. Few native Japanese know any of the English translations, but all Japanese adults know the original Japanese words.
There are two reasons for mixing Japanese in the English text:
- When naturalizing, you will be doing all of your communicating in Japanese. Knowing the English translation (even if the translation is official) will not help you.
- Having the original Japanese term will help you find additional information on the internet about a document (in Japanese), and will allow people searching in Japanese to find these English explanations.
Single Japanese words will have English equivalents beside them whenever possible. This does not mean the English term is the official term or that Japanese officials will understand the English term. And even if the term is the official English term, there is no guarantee that Japanese officials will understand it.