Hello. I am a translator and native speaker of Japanese who reside in Japan.
This job seems to be definitely just for native speakers.
Yes, I can proofread the documents written in Japanese because that's my language.
Some translated sites are written in horrible Japanese.
I can surly promise that you will get natural and correct Japanese documents
which are attracted to Japanese language speakers.
I have been translating English documents into Japanese.
So if it is needed I can refer to the original English documents when I proofread the translated documents.
And I can undertake to revise after once proofreading is finished, if you need it
(even after the project is once done)
Please consider to hire me.