Change work visa to tourist visa for JR pass?

Hello,
I have read many topics about changing a tourist visa to a work visa, but I was wondering whether the opposite would also be possible.

Let's say I have a work visa for 6 months, and only work for 5 months, would it be possible to leave the country and re-enter on a tourist visa, or is it possible to change the work visa to a tourist visa while still residing in Japan?

(After the work period ends I would like to travel and use the JR Pass with a friend, travel dates would still fall inbetween the official 6 months).. I will of course contact my local embassy, unfortunately they are closed today.

The criteria for the rail pass is to have a temporary visitor permit or tourist visa as shown in your passport, a status of residence that does not allow you to live in Japan. It sounds like what you want to do is to cancel your work visa and your right to stay - I have not heard of someone doing that before. Sounds like a lot of paperwork.
However, as a related note, while you could leave the country and come back as a tourist, just to qualify for the JRP, unless you are doing a lot of travel, the cost of your round trip and the pass may not be much less than just paying for your travel. (I'm guessing you'll get one of the 10,000 yen round-trip fares that I see advertised.)

I did this about 15 years ago without any problems at all. It was also quite simple in terms of paperwork. I would assume it can still be done, but you might want to just check with immigration to confirm.

However, I believe you must purchase the JR Pass outside Japan (via a voucher), therefore changing your status of residence within Japan would not allow you to buy a pass.

as mentioned you need to buy the JR voucher outside Japan.
Only changing your status will not be enough

You can buy the JRP voucher in Japan these days (for an extra cost). Alternatively, buy from one of the international sites and have it sent to you address in Japan - that is a very simple option and one I use all the time for my business.

Thank you all for your replies.

I can ask my friend to buy the JR pass for me abroad and bring it with him, as we will meet up in Japan, so on that part it won't be a problem I assume.

Right now I am planning to make a short trip for 2 or 3 days to South-Korea after my work ends, and then re-enter with a tourist visa in Japan to continue my travels with my friend. If I explain at customs I made a quick citytrip to Seoul or Busan for tourist purposes, will this be enough to re-enter without any problems?
Or will I have to officially ask for a change in visa status, but this seems like much more work, so to just be on the safe side.

Thank you again for any insights on this!

if you change the status from working to temporary, you are not eligible for Japan rail pass.
the condition indicates:
(1) You are a foreign tourist visiting Japan from abroad for sight-seeing, under the entry status of "temporary visitor."

you have to come from abroad to Japan as a tourist.