Hi Jess,
All the reputable production service commpanies in Japan have bilingual assistants.
If it is just for a script translation or something like that you could contact independent translators like these ones here:
https://www.interpreters.travel/en/tokyo/10054
Hope that helps.
I hope to see you at FOCUS “the meeting place for international production” in London on the 4th & 5th of December 2018. Attending FOCUS is free for all production professionals. All you need to is register. See REGISTER NOW here:
Homepage
With every good wish,
Murray