Japanese translation

[TakutoJibiki]

Would it be possible to update the Japanese repository to the latest stable version so that I can translate the latest version?
This pull request might be a work in progress.

I plan to fork the English repository (v1.0.0-beta0) and translate it while waiting for the update.
If there are any points to keep in mind when translating, I would like to know them as well.

For Japanese translators:
To share progress and avoid re-translating, please let me know if anyone is working on a translation.
At this time, I only know @harusametime who has contributed to the Japanese repository.