Gaijin Card

A gaijin card, the affectionate name for the Alien Registration Card (外国人登録証明書 gaikokujin tōroku shōmeisho), will function as your main form of ID in Japan. By carrying a gaijin card, you don't need to carry your passport.

Some businesses, such as hotels and manga cafes, will ask for ID upon entering. As a foreigner, your main government-issued ID is your gaijin card, though those with a driver's license may use that instead.

Any changes to the items listed on your gaijin card (such as changing your address or place of employment) are supposed to be reported to city hall - technically within two weeks that said change takes place. If you ever lose your gaijin card, it should be reported to city hall and probably the local police department immediately.