Wikipedia
A is a registry of current residential addresses maintained by local governments in Japan. Japanese law requires each citizen to report his or her current address to the local authorities who compile the information for tax, national health insurance and census purposes.
Once a jūminhyō has been registered with the local government, one can register for various social services including the national health insurance plan. When proof of residence is required, such as for opening a bank account or registering children at a local school district, one needs to obtain a copy of this record from the local government office. Jūminhyō registration is also required in order to officially register a name seal ( inkan), which functions as one's official signature. The jūminhyō is different from a koseki, which is the formal record of a family's history.