Administrative unit in Japan

The bureaucratic administration of Japan is divided into three basic levels; national, prefectural and municipal. Below the national government there are 47 prefectures, six of which are further subdivided into sub-prefectures to better service large geographical areas or remote islands. The municipalities (cities, towns and villages) are the lowest level of government; the twenty most-populated cities outside Tokyo are known as designated cities and are sub-divided into wards.

The top tier of administrative divisions are the 47 prefectural entities: 43 prefectures (県, ken) proper, 2 urban prefectures (府, fu, Osaka and Kyoto), 1 "circuit" (道, dō, Hokkaido), and 1 "metropolis" (都, to, Tokyo). Although different in name they are functionally the same.

"Prefecture" (県, ken) are the most common types of prefectural divisions total of 43 ken. The Classical Chinese character from which this is derived means "county".

Tokyo is referred to as a "metropolis" (都, to) after the dissolution of Tokyo City in 1943, Tōkyō-fu (Tokyo Prefecture) was upgraded into Tōkyō-to and the former Tokyo City's wards were upgraded into special wards. The Classical Chinese character from which this is derived means "capital".

...
Wikipedia