A 7-digit postal code is used to deliver mail. The first two digits of a postal code indicate the prefecture, and the remaining digits indicate a more detailed region.
The postal code system was introduced to improve work efficiency. It started in 1968, 56 years ago. Since February 1998 it has changed to the current 7 digits. By being able to specify even more detailed areas, it has become possible to deliver more efficiently. A sorting machine that automatically sorts postcards and other items by region was put into operation.