What happens when Japanese airport custom officers look at a naturalized Japanese's passport?
Sometimes, when I line up at the èªåã²ãŒã (automated gate) and there's a queue, someone will spot me in the line and run to the booth in preparation for me. They are thinking I'm a foreigner with a re-entry permit; aliens can use the gate, but they are actually "semi-automatic" in that someone still has to remove and collect the re-entry card in their passport. Once they see me scan my passport at the Japanese-only gate and the computer opens the Japanese-only doors after recognizing the Japanese passport, though, they usually quickly leave the booth and go back to the staff area.
When I line up in the Japanese line, nobody (either an official or another passenger waiting in line) has said a word to me about being in the wrong line. When I present my passport to the officer, I'm lucky if they even ask what my purpose for being outside Japan is. Usually they stamp the passport without saying a word. Sometimes they'll say 「ãåž°ããªãã。」 Perhaps it is because of the way I carry myself?
People that have permission to use the automated gates can go in either the automated gate line or the regular Japanese passport line. Whichever is shorter or faster. Some people sometimes want a non-digital record of their entrance or exit into Japan, so they may choose the non-automated line even if they're registered to use the automated line. Sometimes, they will direct Japanese into the visitor or re-entry lines if there is nobody in those lanes. They do this the other way, too: they will sometimes direct the visitors/re-entry people into the Japanese lanes if they are unused and the other lines are congested. If you aren't registered for the automated gates, however, they will never direct you to those lines.
Lately, their are many Japanese and non-Japanese residents who have voluntarily registered their fingerprints for the automated gates. Unfortunately, this means the automated gate is no longer as fast as it used to be as people fumble with scanning their passport and fingerprints by themselves for the first time. The re-entry line for non-Japanese residents is the fastest line, in my observation. But Japanese citizens can't use that without permission.
When I go through duty, if they ask me anything, they ask me the same stock questions I used to get when I was a foreigner: how long was I out of the country, what was the purpose of me being there? Do I have any dutiable or forbidden items?
Compared to regular citizens, airport officials see a lot of different combinations of race & ethnicity and nationality, so outside of statistical assumptions, they tend to believe the paperwork if the paperwork is very official (such as a passport for the home country). Even prior to becoming Japanese, I noticed that when airport officials flipped through my passport and discovered I was a long-term resident, they would switch to Japanese without me prompting them.
Now, I do not know what would happen if you acted "out of profile" for a naturalized citizen. For example: if you presented a Japanese passport and then had difficulty understanding or answering questions posed in Japanese to you. That possibly could trip "warning flags" (as 99% of naturalized Japanese are supposed to understand at least third-grade level Japanese). Just as how they treat a citizen or non-citizen who can't clearly describe what they were doing overseas or give conflicting or hard-to-believe answers, a naturalized Japanese that, for example, can't speak Japanese at all or has difficulty remembering their address or phone number in Japan may get extra precautionary examination.
