Apart from one brief interval, the Liberal Democratic Party has been in power since it was formed in 1955, and every time it picks a new leader internal factions vie for power.
When Prime Minister Taro Aso won a landslide victory in the LDP's presidential election last month, it was the first time in eight years the president was not chosen from the largest faction, which is currently led by former Chief Cabinet Secretary Nobutaka Machimura.
Aso heads one of the smallest LDP factions, and his victory didn't come easy. Starting in 2001, he ran numerous times for party president, and therefore prime minister. The fourth was the charm, and he had to rely on cross-factional support.