Japan has gone through prime ministers at a dizzying rate — Naoto Kan is the sixth in the last four years, and 14th over the past two decades — the highest turnover among the major industrialized countries.
Several factors are behind this revolving door, from the structure of the Diet and the media's power in shaping public opinion, to an electorate that is simply less tolerant of poor leadership.
Since 1990, Britain, whose parliamentary system is closest to Japan's among rich nations, has had five prime ministers, including the recently elected David Cameron. The U.S. has had just four presidents over the same period. Italy comes close with 11 prime ministers, including three people who have served more than once.