Head of Government: The prime minister of Japan is the head of government and the most powerful person in the country. They are appointed by the emperor after being designated by the National Diet. The prime minister appoints other ministers, most of whom are also members of the National Diet, to the Cabinet, which in turn is collectively responsible to the Diet.
National Diet: The National Diet is Japan's parliament and the highest legislative body. It consists of two chambers, the House of Representatives (lower house) and the House of Councillors (upper house). Members of both houses are elected by popular vote.
Party Politics: Japan has a multi-party system, but for most of its post-war history, it has been dominated by the Liberal Democratic Party (LDP). The LDP has held power for the majority of the time since 1955.
Judiciary: The highest judicial body in Japan is the Supreme Court, which is composed of 15 judges appointed by the emperor on the recommendation of the Cabinet. The Supreme Court also has the power of judicial review, which enables it to declare laws passed by the Diet to be unconstitutional.