<P> The Constitution of Japan defines the Emperor to be "the symbol of the State and of the unity of the people". He performs ceremonial duties and holds no real power . Political power is held mainly by the Prime Minister and other elected members of the Diet . The Imperial Throne is succeeded by a member of the Imperial House as designated by the Imperial Household Law . </P> <P> The chief of the executive branch, the Prime Minister, is appointed by the Emperor as directed by the Diet . He is a member of either house of the Diet and must be a civilian . The Cabinet members are nominated by the Prime Minister, and are also required to be civilian . With the Liberal Democratic Party (LDP) in power, it has been convention that the President of the party serves as the Prime Minister . </P> <P> Several political parties exist in Japan, however, the politics of Japan have primarily been dominated by the LDP since 1955, with the DPJ playing an important role as opposition several times . LDP was a ruling party during decades since 1955 . Despite of existence of multiple parties, other parties were completely ignored . Most of the prime ministers were elected from inner factions of LDP . </P> <Table> e d Summary of the 30 August 2009 Japanese House of Representatives election results <Tr> <Th_colspan="2"> Alliances and parties </Th> <Th_colspan="3"> Local constituency vote </Th> <Th_colspan="3"> PR block vote </Th> <Th> Total seats </Th> <Th_colspan="2"> + / − </Th> </Tr> <Tr> <Th> Votes </Th> <Th>% </Th> <Th> Seats </Th> <Th> Votes </Th> <Th>% </Th> <Th> Seats </Th> <Th> (pre - election) </Th> <Th> (last gen . election) </Th> </Tr> <Tr> <Td> </Td> <Td> Democratic Party (DPJ) </Td> <Td> 33,475,335 </Td> <Td> 47.43% </Td> <Td> 221 </Td> <Td> 29,844,799 </Td> <Td> 42.41% </Td> <Td> 87 </Td> <Td> 308 </Td> <Td> 193 </Td> <Td> 195 </Td> </Tr> <Tr> <Td> Social Democratic Party (SDP) </Td> <Td> 1,376,739 </Td> <Td> 1.95% </Td> <Td> </Td> <Td> 3,006,160 </Td> <Td> 4.27% </Td> <Td> </Td> <Td> 7 </Td> <Td> 0 </Td> <Td> 0 </Td> </Tr> <Tr> <Td> People's New Party (PNP) </Td> <Td> 730,570 </Td> <Td> 1.04% </Td> <Td> </Td> <Td> 1,219,767 </Td> <Td> 1.73% </Td> <Td> 0 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> New Party Nippon </Td> <Td> 220,223 </Td> <Td> 0.31% </Td> <Td> </Td> <Td> 528,171 </Td> <Td> 0.75% </Td> <Td> 0 </Td> <Td> </Td> <Td> </Td> <Td> 0 </Td> </Tr> <Tr> <Td> New Party Daichi </Td> <Td_colspan="3"> no district candidates </Td> <Td> 433,122 </Td> <Td> 0.62% </Td> <Td> </Td> <Td> </Td> <Td> 0 </Td> <Td> 0 </Td> </Tr> <Tr> <Td> Ruling DPJ--SDP--PNP coalition & parliamentary allies </Td> <Td> 35,802,866 </Td> <Td> 50.73% </Td> <Td> 228 </Td> <Td> 35,032,019 </Td> <Td> 49.78% </Td> <Td> 92 </Td> <Td> 320 </Td> <Td> 193 </Td> <Td> 194 </Td> </Tr> <Tr> <Td> </Td> <Td> Liberal Democratic Party (LDP) </Td> <Td> 27,301,982 </Td> <Td> 38.68% </Td> <Td> 64 </Td> <Td> 18,810,217 </Td> <Td> 26.73% </Td> <Td> 55 </Td> <Td> 119 </Td> <Td> 181 </Td> <Td> 177 </Td> </Tr> <Tr> <Td> New Komeito Party (NKP) </Td> <Td> 782,984 </Td> <Td> 1.11% </Td> <Td> 0 </Td> <Td> 8,054,007 </Td> <Td> 11.45% </Td> <Td> 21 </Td> <Td> 21 </Td> <Td> 10 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> Japan Renaissance Party </Td> <Td> 36,650 </Td> <Td> 0.05% </Td> <Td> 0 </Td> <Td> 58,141 </Td> <Td> 0.08% </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> </Td> <Td> 0 </Td> </Tr> <Tr> <Td> Opposition LDP--NKP coalition & parliamentary allies </Td> <Td> 28,121,613 </Td> <Td> 39.84% </Td> <Td> 64 </Td> <Td> 26,922,365 </Td> <Td> 38.26% </Td> <Td> 76 </Td> <Td> 140 </Td> <Td> 192 </Td> <Td> 187 </Td> </Tr> <Tr> <Td> </Td> <Td> Japanese Communist Party (JCP) </Td> <Td> 2,978,354 </Td> <Td> 4.22% </Td> <Td> 0 </Td> <Td> 4,943,886 </Td> <Td> 7.03% </Td> <Td> 9 </Td> <Td> 9 </Td> <Td> 0 </Td> <Td> 0 </Td> </Tr> <Tr> <Td> Your Party (YP) </Td> <Td> 615,244 </Td> <Td> 0.87% </Td> <Td> </Td> <Td> 3,005,199 </Td> <Td> 4.27% </Td> <Td> </Td> <Td> 5 </Td> <Td> </Td> <Td> 5 </Td> </Tr> <Tr> <Td> Others </Td> <Td> 1,077,543 </Td> <Td> 1.53% </Td> <Td> 0 </Td> <Td> 466,786 </Td> <Td> 0.66% </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0 </Td> </Tr> <Tr> <Td> Independents </Td> <Td> 1,986,056 </Td> <Td> 2.81% </Td> <Td> 6 </Td> <Td_colspan="3">--</Td> <Td> 6 </Td> <Td> 0 </Td> <Td> 12 </Td> </Tr> <Tr> <Td_colspan="2"> Totals </Td> <Td> 70,581,680 </Td> <Td> 100.00% </Td> <Td> 300 </Td> <Td> 70,370,255 </Td> <Td> 100.00% </Td> <Td> 180 </Td> <Td> 480 </Td> <Td> 2 * </Td> <Td> 0 </Td> </Tr> <Tr> <Td_colspan="2"> Turnout </Td> <Td_colspan="3"> 69.28% </Td> <Td_colspan="3"> 69.27% </Td> <Td_colspan="3"> * (vacant seats) </Td> </Tr> </Table>

Which political party has dominated japanese politics since the end of world war ii