Wikipedia
Koenkai (後援会; engl. "local support groups") are an invaluable tool of Japanese Diet members, especially of the Liberal Democratic Party (LDP). These groups serve as pipelines through which funds and other support are conveyed to legislators and through which the legislators can distribute favors to constituents in return. To avoid the stringent legal restrictions on political activity outside of designated campaign times, koenkai sponsor year-round cultural, social, and "educational" activities. In the prewar years, having an invincible, or "iron," constituency depended on gaining the support of landlords and other local notables. These people delivered blocks of rural votes to the candidates they favored. In the more pluralistic postwar period, local bosses were much weaker, and building a strong constituency base was much more difficult and costly. Tanaka Kakuei used his "iron constituency" in rural Niigata Prefecture to build a formidable, nationwide political machine. But other politicians, like Ito Masayoshi, were so popular in their districts that they could refrain, to some extent, from money politics and promote a "clean" image. Koenkai remained particularly important in the overrepresented rural areas, where paternalistic, old-style politics flourished and where the LDP, despite disaffection during the late 1980s over agricultural liberalization policies, had its strongest support.
In the classic oyabun-kobun manner, local people who were consistently loyal to a figure like Tanaka became favored recipients of government largesse. In the 1980s, his own third electoral district in Niigata was the nation's top beneficiary in per capita public works spending. Benefits included stops on the Shinkansen bullet train to Tokyo and the cutting of a tunnel through a mountain to serve a hamlet of sixty people. Another fortunate area was Takeshita Noboru's district in Shimane Prefecture on the Sea of Japan.
The importance of local loyalties is also reflected in the widespread practice of a second generation's "inheriting" Diet seats from fathers or fathers-in-law. This trend is found predominantly, although not exclusively, in the LDP. In the February 1990 election, for example, forty-three second-generation candidates ran: twenty-two, including twelve LDP candidates, were successful. They included the sons of former prime ministers Suzuki Zenko and Fukuda Takeo, although a son-in-law of Tanaka Kakuei lost in a district different from his father-in-law's.