A presidential system like that of the United States sets the maximum tenure that a president can serve. In South Korea, the maximum tenure is a single five-year term, while in the U.S. a president can serve up to two consecutive four-year terms (for a total eight years). In Japan, which has a parliamentary Cabinet system, there is no maximum tenure for a prime minister. But there are rules in the governing party that set term limits for the party leader (president in the case of the Liberal Democratic Party). Under the parliamentary Cabinet system, the top leader of the ruling party will in principle head the administrative branch as prime minister. In practice, the term of the ruling party chief sets the tenure of the prime minister.
Previously, the LDP, the main party in the ruling coalition, set the maximum tenure of its president to two consecutive three-year terms (for a total of six years). The past long-running LDP-led administrations in recent history, such as Prime Minister Yasuhiro Nakasone’s (1982-87) and Prime Minister Junichiro Koizumi’s (2001-2006), ended in just shy of six years.