Here in Argentina each person has a "unique"[1] DNI number that kakas tracking easy. It's like the SSN in USA, but here it-s not a secret and it appears in many documents. Do they have something like that in Japan?
[1] There use to be many burocratic errors that make the number not unique For example they assigned a town a range 30.000.000-30.000.999 and the next town the range 30.001.000-30.001.999, but after the first town used all their numbers they continue sequentially and overlapped the numbers of the other town. It's supposed to be fixed now, but old people numbers are full of surprises. One of my coworkers had to merge many big data bases and he still get nightmares about deduplications in spite the DNI is supposed to be a go unique identifier.
[1] There use to be many burocratic errors that make the number not unique For example they assigned a town a range 30.000.000-30.000.999 and the next town the range 30.001.000-30.001.999, but after the first town used all their numbers they continue sequentially and overlapped the numbers of the other town. It's supposed to be fixed now, but old people numbers are full of surprises. One of my coworkers had to merge many big data bases and he still get nightmares about deduplications in spite the DNI is supposed to be a go unique identifier.