Originally Posted by
kentauta
I would say probably forever. I remember reading an article about Japanese police keeping fingerprint/DNA collected from citizens on a voluntary basis for future use without any consent.
There was a huge brouhaha about this in the early 90's when they ended fingerprints on the "gaijin-cards". Roll ahead to the 2000's and they collect your fingerprints each time you enter , whether you have residency or not.