Japan is a constitutional monarchy with a parliamentary government. The country's constitution was made on May 3, 1947 right when the U.S. took control of Japan following World War II. Under the constitution, Japan has "universal adult suffrage" with a secret ballot for all elective offices. Which basically means that all legal adults in the country can vote privately.
Just like the U.S. their government is made up of an executive branch responsible to the legislative branch and an independent judicial branch. The national parliament, a. k. a "The Diet", is made up of (somewhat like the U.S.) two houses: a House of Representatives (lower house) of 500 members and a House of Councillors (upper house) of 252 members. Executive power is given to a cabinet made up of a prime minister and ministers of state. Although, all of those prime ministers and ministers of state have to be civilians. The prime minister must be a member of "The Diet", usually in the House of Representatives, and is chosen by his others in that house. The prime minister has the power to appoint and remove ministers, and mostly all have have to be Diet members.
Japan's judicial system, which, again, is based off of the U.S. traditions, consists of several levels of courts, and the Supreme Court is the "final judicial authority" or the court that has the last word in any judicial issue. The constitution includes a bill of rights similar to the United States Bill of Rights, and the Supreme Court has the right of "judicial review". Japanese courts do not employ a jury, and there are no administrative courts or claims courts like we have in the U.S. Court decisions are made with "legal statutes"; only Supreme Court decisions have any direct effect on later issues of the law. Japan does not have a federal system. It mostly depends heavily on the central government for help. Governors of regions in Japan (lik the 50 states in the U.S. ), mayors of large cities or towns, and state and city wide assembly members are "popularly" elected for four-year terms.
In the lower house of the Diet, 300 members are elected in single-member districts and another 200 members are elected on equally in 11 regions of the country. Lower house members serve for four years, or until the prime minister changes the Diet, basically, whichever comes first. In the upper house, 152 members are elected in regional districts, while 100 are elected in nation-wide balloting. Upper house members serve for six years. The lower house is the more powerful of the two parliamentary houses. If the upper and lower houses cant agree on the choice of prime minister, the lower house takes charge, and budgets and treaties can be passed only with action by the lower house.
Japan is a multiparty democracy that has experienced great stability in the postwar period. From 1955 until 1993, the conservative Liberal Democratic Party (LDP) ruled Japan without interruption. During that period, the main opposition party in the Diet was the Japan Socialist Party (JSP), which relied heavily on Japan's labor unions for support, and which in recent years has experienced a sharp decline in popularity. In 1993, a multiparty "alliance" took control without the LDP.
However, the LDP was returned to power in June 1994 in an unpredictable "alliance" with the JSP and a small party, the Sakigake. In January, 1995 the LDP reclaimed the prime minister's chair, when Ryu taro Hashimoto replaced his JSP alliance partner, Tomi ichi Mura yama. Currently the largest parties in the parliament are the New Frontier Party and the Democratic Party of Japan, formed in 1996; all political parties except the Japan Communist Party (JCP) support the security alliance between the United States and Japan.