Leaving Japan for more than a year

I have to take care of a sick and disabled family member for some time (not sure but could be multiple years) and will leave Japan in the end of this month, giving my moving out notice to the ward office.

Since I have permanent residence status, I will also get a 5 years multiple re-entry permit in the next days so that it's easy for me to come back and live in Japan again. But I have a few questions here:

1. Even when I have left and , I want to come back every year for around 2-3 month or so for work purposes, because I will continue to work for my Japanese employer. The exact duration will depend on whether I can organize care for this time period.

Will this trigger any problems when I come back for such a long period?

2. What happens to my Japanese drivers license - when I come back to Japan, can I use it or does it become invalid because I don't have an address anymore? What happens if I want to extend it?

3. The chance is unlikely, but in case I have to care for longer than 5 years, could I even get another re-entry permit? Will there be problems with immigrations? I can get documents from the doctors in my country that can prove that I have to take care, but I wonder if there is still a time limit or something like that. That makes me feel scared a little bit.

I hope that my plan can work out, because I really want to live in Japan, but currently I have no other choice but return to my home country for a while.

I want to come back every year
You are coming back every year - most of the problems you describe simply do not apply. Short term absence - no issue.

2. your driver license card is still valid. but, you can't use it as ID. if police finds the incorrectness of your address, they may advise you to fix your address, but still the license is valid. when the expiry date is coming soon, they will send you the post card for renewal. you should fix an address where someone can receive your post mails.

Thanks for the replies!

I wonder what happens if I don't have an address that I could use in this case (i.e. no friend that I want to bother with this).

But good to know that it will stay valid. I wonder though, what will happen if something happens (e.g. I get a speeding ticket) and they send it to the address on my drivers license but it doesn't reach me. Hm...

Regarding the post (I wouldn’t be worried about a speeding ticket, because you are not in Japan… so why would you get a Japanese speeding ticket, but you could get other post): you write that you will continue working for your japanese company. Why not agree with them that your letters will be sent to their address? That’s what I did when I moved from Japan. You can go to the post office and have a temporary deviation off your post arranged.