Japan has a constitutional monarchy with a parliamentary system. The Emperor is the ceremonial head of state, while the Prime Minister serves as the head of government and is typically the leader of the ruling party or coalition. The National Diet, a bicameral legislature consisting of the House of Representatives and the House of Councillors, is the supreme law-making body. The Cabinet, led by the Prime Minister, holds executive power and is responsible for running the government. The judiciary is independent, with the Supreme Court at its apex. This structure embodies separation of powers among the legislative, executive, and judicial branches.