Japan has had just two socialist prime ministers: Katayama Tetsu (1887–1978) from May 1947 until March 1948, and Murayama Tomiichi (1924–) from June 1994 until January 1996.1 Nearly fifty years separate the two leaders, but their premierships and the similarities between them encapsulate the fate of social democracy in Japan. Both Katayama and Maruyama became prime minister as part of coalition cabinets with their erstwhile conservative rivals as part of governments of national unity during political crises. Both paid dearly for the compromise. Their short terms in office, eleven months in Katayama’s case and eighteen months in Murayama’s, were followed by electoral disasters for their party with long-lasting consequences. Following Katayama’s premiership, the Japan Socialist Party faced nearly fifty years in the political wilderness. After Murayama resigned in favour of his coalition partner, his party split. At the October 1996 election the party was reduced to a shell of its former self with just fifteen seats in Japan’s Lower House.