The Japanese system of government is similar to that of the United States and other major Western countries in many ways. Some of the basic features that it has in common with these other countries include (1) respect for fundamental human rights, (2) sovereignty of the people, and (3) government by politicians chosen by election. This type of government is called democracy, and it aims to serve the people and do their will.
The governments of democracies have three branches: legislative, executive, and judiciary, which operate in a system of checks and balances. In the United States, the head of the executive branch is the president, but in Japan the head is called prime minister. The way the two are chosen is also different. The American president is chosen in a direct vote by the people of the whole country, but the Japanese prime minister is elected by the members of the legislature, or National Diet, as it is called in Japan's case. This is very much like the system used in Britain and many other democracies. (The members of the Diet are chosen by the people, just as the members of the U.S. Congress and British Parliament are.) In the United States, the president appoints members of the cabinet, called secretaries, who head the various departments of the federal government. The Japanese prime minister also appoints cabinet members, but they are called ministers, and the departments they head are mostly called ministries, such as the Ministry of Finance (corresponding to the U.S. Treasury Department) and the Ministry of Foreign Affairs (corresponding to the U.S. Department of State). In the United States, secretaries do not have to be members of Congress, but in Japan a majority of the cabinet members must be Diet members.
Both the U.S. president and the Japanese prime minister are ultimately responsible to the people of the nation. The president answers directly to the people as an individual and serves for a term of four years until the next election. But the prime minister shares responsibility with all the cabinet members, and they answer not directly to the people but rather to the legislature. If the legislators stop supporting the cabinet at any time, either the cabinet ministers, including the prime minister, must resign, or the prime minister must call a general election. Overall the Japanese system is designed to keep any single individual from having very great power; this seems to have been a feature of Japanese government since early times.