I recently found out that I'm going to be moving to Tokyo! I'm trying to research the city. Have you been to Tokyo?
Yes, I have been many times. The Greater Tokyo Area has the highest population than any other metropolitan area in the world.
That's incredible! What is the population of Tokyo?
It's around 9 million. They have a good transportation system there. every part of Greater Tokyo has rail or road transport services.
Oh good! It will be easy to get around without having to drive! What is the area like that surrounds Tokyo? Are there any natural areas?
mi), giving it a population density of 2,642 person/km. It is the second largest single metropolitan area in the world in terms of built-up or urban function landmass at 8,547 km (3,300 mi), behind only New York City at 11,642 km (4,495 mi).
The area has the largest metropolitan economy in the world, with a total GDP (nominal) of approximately $2 trillion (¥165 trillion) in 2008. According to research published by PricewaterhouseCoopers,
city is defined as, "one having a population of 2 million and above".
Japan.
In Japan, it is division that has been set separately from administrative areas in order to define wide urban areas by the Statistics Bureau of the Ministry of Internal Affairs and Communications. 
The Greater Tokyo Area is the most populous metropolitan area in the world. 
- Central City (中心市)
- Those of the greater metropolitan areas are the 23 special wards in the metropolis of Tokyo and other designated cities.