All registered foreigners living in Japan carry one of these, a Gaikokijin Toroku Shomeisho, aka the Alien Registration Card, which you get from the City Office in your local town when you first come to Japan to live. It lists the name, current address, employment status and photograph of the person in question, and generally provides whatever information authorities might need access to. It’s quite an analog system, actually — when information needs to be updated, the changes are hand-written on the back of the card by a City Office employee, along with a special stamp that proves that an authorized official has made the change. Theoretically, any policeman can ask to see the registration card of any foreigner, but I’ve never been asked to show mine and have always found Japanese policemen to be very courteous and nice.
