As I mentioned I dont really know much about the pension system. My understanding is when reaching retirement, pensions can only be deposited into a Japanese bank account. If you have left Japan and no longer have any residency then you cannot continue to hold a Japanese account. So for a foreigner taking as much as you can when you leave seems to be the only option! Keep in mind this is your money anyway as a monthly “pension insurance” fee will be deducted from you salary. Its not what I would consider sufficient to sustain retirement though!