* The  of Tokyo comprise the area formerly incorporated as Tokyo City. The special wards use the word "city" in their official English name (e.g. Chiyoda City). The wards differ from other cities in having a unique administrative relationship with the prefectural government. Certain municipal functions, such as waterworks, sewerage, and fire-fighting, are handled by the Tokyo Metropolitan Government. To pay for the added administrative costs, the prefecture collects municipal taxes, which would usually be levied by the city. The "three central wards" of Tokyo – Chiyoda, Chūō and Minato – are the business core of the city, with a daytime population more than seven times higher than their nighttime population. Chiyoda Ward is unique in that it is in the very heart of the former Tokyo City, yet is one of the least populated wards. It is occupied by many major Japanese companies and is also the seat of the national government, and the Japanese emperor. It is often called the "political center" of the country. Akihabara, known for being an otaku cultural center and a shopping district for computer goods, is also in Chiyoda.