Retirement money and change country timing.

Hello,
I am sorry I know this as been asked many times, but with a lot of different angles, so I wanted to make a new thread with a few question of my own. Also, the below might be very very wrong. So just read the question might be better than reading my assumptions.

I am currently living in Japan since 2016. I started my first Arubaito in 2017 in a restaurant yen (~90,000yen/month) and i kept working till today as software dev (500,000yen/month

So technically, i worked here for about 6 years with an average of i would say 300,000y/month.

Now from what I very quickly calculated this would mean around 2,000,000yen of Nenkin put aside (might be way off but it’s just as rought exemple).

I am still unsure if remaining in Japan, or not, and I heard/read the nenkin is “refundable” under a certain amount of year (i believe 5) but lost over a certain amount (so over 5). But in the case you become PR, you are eligible to get the pension once you retire like a normal citizen.

My question are

– is it correct that over 5 year of “cotisation” the amount i would get but leaving the country would not include additional years ?
– if the above is correct, how is it calculated, is it the 5 most recent, or 5 first year ?
– assuming you would want to leave the country, basically you should leave either tin the first 5 years or after obtaining a PR?
– how does it work after obtaining PR but eventually working in another country other than Japan (but maintain the PR by coming in Japan for remote work often)