The Liberal Democratic Party (LDP), which had been ruling almost uninterruptedly in Japan from 1955, had to face its biggest defeat at the end of August 2009. In fact, the opposition parties led by the Democratic Party of Japan (DPJ) were able to win a two thirds majority in the Lower House and to revolutionize the old power relations. This outcome sounds even more outstanding when we think that this turnover took place only 4 years after the LDP’s biggest victory in history. But at the time, it was led by charismatic Koizumi, who was probably more in line with the opposition parties rather than with the koenkai of the LDP, so that it is not wrong to say that these two results were somehow related. The DPJ’s success, though, was based less on its own attractiveness than on the content and personal decay of the DPJ and the consequent mood for change that came up in Japan. Among the factors that should be considered while analyzing the LDP’s failure, there are unpopularity of its leaders and its incapability to adapt to the new electoral system. However, it was not only the LDP that paved its way to self-destruction, but also the DPJ that efficiently undermined the political scenario in 2009: the extent of its victory should be attributed to its careful election preparation in the previous months and to its attention to the people’s needs and requests. Lastly, there are external factors that should be taken into consideration before stating that it was either the DPJ’s win or the LDP’s loss.