[allhailhata]

Basically,Japan doesn't accept foreigners as nurse.Although there is a Medical Services Visa.

Only Filipino and Indonesian can be accepted as a nurse.There are Economic Partnership Agreement between Japan and that two countries.
They should get training and pass the exam in Japan.This program started recently.

Only 3 foreigners passed the last exam.　251 of them couldn't pass.On the other hand,90% of Japanese passed.It is difficult for foreigners to pass the exam in Japanese.

If you have already Japanese　permanent residency(like zainichi Korean or Chinese),you can be nurse in Japan.But you should pass the exam too.
Japanese Brazilian can get visa easily.On the other hand, normal Brazilian can't get Japanese visa with which they can work in Japan easily.

I'm sure you don't know any Brazilian(mulato or not,transexual or not) working as a nurse in Japan.I(native Japanese) don't know too.