Most Western commentators on Japan's recent change of leadership have focused on the extraordinarily short tenure of former prime minister Yukio Hatoyama, who resigned last week after spending fewer than nine months in office. But for all of its brevity in office, Hatoyama's reign was by no means the shortest. Four prime ministers in post-war Japan have had even shorter tenures. And the previous three leaders from the former Liberal Democrat government each served only about one year (one should probably excuse Taro Aso, who naturally and properly resigned after losing an election).