Does a new passport number mean new records?

Question

And let me explain why I ask this. In the last few years I have been travelling too many times to Japan as a tourist (visa free) due to my girlfriend living there.

Although I don't exceed the unofficial limit of 180 days within a rolling year (Japanese immigration official told me about this limit), so many visits to Japan started to get suspicious and I get asked too often.

This leads me to the two following questions:

1. When you get a new passport with a new number, how do immigration authorities track your previous trips to some particular country? Is it just about your full name? Perhaps some biometric information? Some other persistent ID? I guess it cannot be about full name, as there are many citizes with similar full names.

2. Would a passport renewal (i.e., new blank passport) help in my case? At least immigration officials wouldn't notice all the Japan stamps I already have. Or perhaps they don't care about the stamps and they get all the data they care about from their computers?

Answer 1

When you get a new passport with a new number, how do immigration authorities track your previous trips to some particular country?

Other information in the passport, possibly including fingerprints or facial recognition. Even without those, ...

Is it just about your full name?

No. There is also the date of birth. Many countries' passports also have the place of birth, and some still have identifying characteristics such as height. Some countries include the bearer's national identification number in the passport, which would make it trivially easy to link different passports issued to the same person.

Perhaps some biometric information?

Indeed. Most passports contain biometric data in an RFID chip; even without that, a country could scan and save the passport photograph (I don't know whether any country does that, much less whether Japan does).

Some other persistent ID? I guess it cannot be about full name, as there are many citizens with similar full names.

Indeed you are right: it cannot be about full name. But passports do not contain only the full name.

Would a passport renewal (i.e., new blank passport) help in my case?

Possibly. If you try it, please come back and post an answer.

At least immigration officials wouldn't notice all the Japan stamps I already have. Or perhaps they don't care about the stamps and they get all the data they care about from their computers?

Again, if they can link the new passport to the old one, they may indeed get all the data from the computer. For all you know, they might have an agreement with your country of citizenship whereby they receive data to link passport numbers that have been issued to the same individual.

Answer 2

You cannot help them being suspicious if you are in a category of traveller that looks high risk for overstay, even if you are doing everything legally.

Some factors:

1. romantic partner in the country
2. frequent visits
3. long visits
4. being close to the upper allowable limit

Basically, the less you seem like an ordinary tourist or business traveller, the more hassle you will get. Anecdotally, dressing better might change your treatment, and having paperwork on you about your finances and job/studies at home would be a good idea.

Changing your passport will do nothing. Everyone changes passports over time and a significant percentage of people change their names (at marriage or otherwise). The passport number is not the primary way of identifying an individual - they still have your name, birthdate and place, fingerprints, etc.