Matt Yglesias has questions about Japan's Liberal Democratic Party, a.k.a "the one that always wins."
I'm hardly an expert on contemporary Japanese politics, but I did read Tim Weiner's gripping new history of the CIA, Legacy of Ashes. Here's what Weiner has to say about the LDP (pp. 116-121):
The most crucial interaction between the CIA and the Liberal Democratic Party was the exchange of information for money. It was used to support the party and to recruit informers within it. The Americans established paid relationships with promising young men who became, a generation later, members of parliament, ministers, and elder statesmen. Together they promoted the LDP and subverted Japan's Socialist Party and labor unions. [...]
The Japanese came to describe the political system created with the CIA's support as kozo oshoku—"structural corruption." The CIA's payoffs went on into the 1970s. The structural corruption of the political life of Japan continued long thereafter.
"We ran Japan during the occupation, and we ran it a different way in these years after the occupation," said the CIA's Horace Feldman, who served as station chief in Tokyo. "General MacArthur had his ways. We had ours."
The idea was to prevent communist subversion. And it worked! I'm tempted to ask, "At what price?" but it seems that the price was not terribly high. Japan's a pretty stable democracy now, though its justice system needs some work.