Shinjuku Is Actually Its Own City
While it appears to be just a district within Tokyo, Shinjuku is legally classified as an independent city. It functions as a self-governing municipality with its own mayor and administrative authority.
Tokyo is unique because it is technically a prefecture made up of many individual cities, towns, and villages. Shinjuku is one of the 23 special wards that operate with the autonomy of a city government. This structure allows Shinjuku to manage its own public services and local taxes separately from the rest of the metropolis. It is a fascinating example of how a dense urban hub maintains its own distinct political identity.
Source: Shinjuku