Chiyoda, Tokyo in the context of "Uchisaiwaichō"

Tokyo, officially the Tokyo Metropolis, is the capital and most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is one of the most populous urban areas in the world. The Greater Tokyo Area, which includes Tokyo and parts of six neighboring prefectures, is the most populous metropolitan area in the world, with 41 million residents as of 2024.

Lying at the head of Tokyo Bay, Tokyo is part of the Kantō region, on the central coast of Honshu, Japan's largest island. It is Japan's economic center and the seat of the Japanese government and the Emperor of Japan. The Tokyo Metropolitan Government administers Tokyo's central 23 special wards, which formerly made up Tokyo City; various commuter towns and suburbs in its western area; and two outlying island chains, the Tokyo Islands. Although most of the world recognizes Tokyo as a city, since 1943 its governing structure has been more akin to that of a prefecture, with an accompanying Governor and Assembly taking precedence over the smaller municipal governments that make up the metropolis. Special wards in Tokyo include Chiyoda, the site of the National Diet Building and the Tokyo Imperial Palace; Shinjuku, the city's administrative center; and Shibuya, a hub of commerce and business.

The National Diet Building (国会議事堂, Kokkai-gijidō) is the building where both houses of the National Diet of Japan meet. It is located at Nagatachō 1-chome 7–1, Chiyoda, Tokyo.

Sessions of the House of Representatives take place in the south wing and sessions of the House of Councillors in the north wing.

The Imperial Palace (皇居, Kōkyo; lit. 'Imperial Residence') is the main residence of the emperor of Japan. It is a large park-like area located in the Chiyoda district of the Chiyoda ward of Tokyo and contains several buildings including the Fukiage Palace (吹上御所, Fukiage gosho) where the emperor has his living quarters, the main palace (宮殿, Kyūden) where various ceremonies and receptions take place, some residences of the Imperial Family, an archive, museums and administrative offices.

The 1.15-square-kilometer (0.44 sq mi) palace grounds and gardens are built on the site of the old Edo Castle.

The prime minister of Japan (内閣総理大臣, Naikaku Sōri Daijin; Japanese pronunciation: [naꜜi.ka.kɯ | soː.ɾʲi daꜜi.dʑiɴ]) is the head of government of Japan. The prime minister chairs the Cabinet of Japan and has the ability to select and dismiss its ministers of state. The prime minister also serves as the commander-in-chief of the Japan Self Defence Forces. The incumbent prime minister, Sanae Takaichi, took office on 21 October 2025; she is the first woman to serve as either president of the Liberal Democratic Party or prime minister.

The National Diet (parliament) nominates the prime minister from among its members (typically from among the members of the House of Representatives). They are then formally appointed by the emperor. The prime minister must retain the confidence of the House of Representatives to remain in office. The prime minister lives and works at the Naikaku Sōri Daijin Kantei (Prime Minister's Official Residence) in Nagatachō, Chiyoda, Tokyo, close to the National Diet Building.

The National Diet (国会, Kokkai; Japanese pronunciation: [kok̚.kai]) is the national legislature of Japan. It is composed of a lower house, called the House of Representatives (衆議院, Shūgiin), and an upper house, the House of Councillors (参議院, Sangiin). Both houses are directly elected under a parallel voting system. In addition to passing laws, the Diet is formally responsible for nominating the prime minister. The Diet was first established as the Imperial Diet in 1890 under the Meiji Constitution, and took its current form in 1947 upon the adoption of the post-war constitution. Both houses meet in the National Diet Building (国会議事堂, Kokkai-gijidō) in Nagatachō, Chiyoda, Tokyo.

The Imperial Investiture (親任式, Shinninshiki) is an official inauguration ceremony whereby the Emperor of Japan formally appoints the Prime Minister of Japan or the Chief Justice of Japan to office. In practice, the Prime Minister is nominated by the Diet, while the Chief Justice is nominated by the Cabinet. The Emperor is constitutionally required to appoint the nominated person, without the right to decline appointment.

During the time period of the Empire of Japan, as the Emperor was the source of executive authority, there were also investitures held for military officials. Such appointees were called the Shinninkan (親任官).

The Supreme Court of Japan (最高裁判所, Saikō-Saibansho; called 最高裁 Saikō-Sai for short), located in Hayabusachō, Chiyoda, Tokyo, is the highest court in Japan. It has ultimate judicial authority to interpret the Japanese constitution and decide questions of national law. It has the power of judicial review, which allows it to determine the constitutionality of any law or official act.