Japan is a constitutional monarchy, similar to the United Kingdom. The head of state is Emperor Naruhito, who, along with his family, is said to be a descendant of Amaterasu, the Shinto sun goddess. Today, the Emperor’s role is purely ceremonial. After World War II, Emperor Naruhito’s grandfather, Emperor Hirohito (known posthumously as Emperor Shōwa), was forced to renounce claims of divine status. When Japan’s current constitution was enacted in 1947, the Emperor was designated as “the symbol of the state and the unity of the people.”
Japan’s government follows a parliamentary system similar to the Westminster model. The country is governed by the National Diet, which consists of two houses: the House of Representatives (the lower house) and the House of Councillors (the upper house). The Prime Minister, who is elected by the Diet, serves as the head of government, while the Emperor remains a symbolic figure.
The members of both houses are elected by the public. Voting in Japan is not compulsory and is open to Japanese citizens aged 18 or older (lowered from 20 in 2016). To become a member of the Diet, one must be of Japanese nationality and at least 25 years old for the House of Representatives or 30 years old for the House of Councillors.
The House of Representatives has 465 seats, with members elected through a combination of single-member districts and proportional representation. Elections are held every four years. The House of Councillors consists of 248 members, with representatives elected from both prefectural constituencies and nationwide party lists. Elections for the House of Councillors are held every six years, with half of the seats contested every three years.
The Prime Minister is elected by both houses of the Diet, though in practice, the leader of the majority party in the House of Representatives usually assumes the role. The Emperor formally appoints the Prime Minister but does not influence the decision. Since 1947, Japan has had a relatively high turnover of Prime Ministers, with many serving for short periods. One of the longest-serving Prime Ministers in recent history was Junichiro Koizumi, who held office for 1,979 days from April 2001 to September 2006.
For a bill to become law, it must pass both houses of the Diet before being promulgated by the Emperor. The Emperor has no power to reject legislation and must formally endorse the Diet’s decision.
Before the 1947 constitution, Japan’s government functioned under the Meiji Constitution, where the Imperial Diet operated similarly to today but with key differences. The upper house was known as the House of Peers and was composed mainly of aristocrats, princes, and imperial appointees. The Emperor also had the power to override and veto parliamentary decisions.
Both the pre-war Imperial Diet and the modern National Diet have convened in the National Diet Building in Chiyoda, Tokyo. Completed in 1936, the building was one of the few in the area to survive the extensive air raids of World War II. The Prime Minister’s residence, built in 1929 and located just behind the Diet building, also survived. In contrast, the nearby Imperial Palace sustained significant damage during the war.
