>>532144450
>>532145068
No, you don't lose anything for unlinking, just make sure your in-game account is logged in on a device before unlinking, you don't want to lose it forever. Cygames account is throwaway-able, you can link and unlink to any account you want anytime you want.
>(in JP region)
If you are trying to buy in JPY, this doesn't work (at least not when I tried). You need your in-game account to be Japan, AND then your cygames account to be in the same region. But do it anyways and report back