[dirtyroboto]

I would suggest that for this sector you would be first and foremost required to know Japanese to JLPT Lvl 2 and have a very good understanding of Kanji.
You would have to resit all of your tests in Japanese using Kanji.

You would need to read medical documents in Kanji and to such a level that you could be trusted not to make mistakes that could endanger a person.

It may be very well that you can attend to people in you country where the scripts are in English, but you would need to do this in Japanese without mistake.

I wish you good luck, but it is a very hard road to take. I also admire your wishes to help other people. But I also feel sad that you choose such a hard way to achive them.