Core cities of Japan

is a defined class or category of Japanese cities. It is a local administrative division created by the national government. All core cities have a population greater than 300,000. 
History.
The core cities were created because of the Local Autonomy Law of Japan. Each city does many of the things normally done by prefectures. 
List.
Core cities were recognized starting in 1996. There are 40+ of these cities, including