Leading article: A victory with the potential to transform Japan

But modernising Tokyo's entrenched political system will not be easy

A change of government as the result of a free and fair election is the ultimate validation of the democratic process. In evicting the ruling Liberal Democratic Party so decisively yesterday, the Japanese showed the strength of their democracy. They also showed, even more decisively, their disillusionment with the status quo and, maybe, their openness to change.

That is a hopeful and exciting prospect. Japanese society, and even more its politics, has been stuck in a highly traditional mould. There is nothing wrong with tradition and cultural specificity until they constrain a nation's positive development and cramp its international style. In Japan, it seemed, that point had been reached a decade ago, only to be postponed when Junichiro Koizumi bounded on to the scene. When he left office, the decline of the LDP set in anew.

How much change the Japanese are really ready for will emerge only with time. The voters had very particular, short-term complaints about the government of Taro Aso. Personally, he was a lacklustre politician, the latest in a succession of weak prime ministers who followed Mr Koizumi. He was unlucky, too, in that the international economic crisis, which hit Japan hard, arrived just as Mr Aso took office. If the LDP had had any chance of staying in power, it was probably lost then. The weak economy, and unemployment in particular, was a central issue in the campaign.

Even so, the scale of the party's defeat exceeded forecasts. In power more or less continuously for half a century, the LDP did not suffer a loss so much as a rout. The opposition Democratic Party of Japan, led by Yukio Hatoyama, won almost two thirds of seats in the lower house. It will not need to form a coalition to govern.

For people more used to degrees of change – if any – the Japanese have voted in a government whose policies differ quite markedly from those of its predecessor. On the economy, the DPJ has pledged to create jobs and help consumers rather than focusing on big corporations as the driving force of wealth. This shift will be as hard for the new government to effect as it will be for Japanese business to accept. But even if moves in this direction are only modest, they could still entail quite big shifts in the way Japan works.

A less visible, but potentially even more significant, change could come with the DPJ's approach to foreign policy. In time, the world could find that it is dealing with a more outward- looking power, which treats its alignment with the United States more conditionally. Mr Hatoyama has also promised more Japanese help for peace-keeping and more realism in dealing with its vast neighbours, Russia and China.

In part, this marks Japan's belated recognition that the Cold War is over. But it also suggests that Tokyo might come to look like a more regional power, interested in warmer relations with Russia – where even trade is still impeded by the Kurile Islands dispute – and, more crucially, with China. As prime minister, Shinzo Abe began a rapprochement with China in 2006; Mr Hatoyama is primed to pick up where he left off.

Change and modernisation were, naturally, at the heart of the DPJ's campaign. But Japan's ingrained conservatism, its aversion to risk and its entrenched business and bureaucratic elites are all reasons why a DPJ government may, in the end, make less difference than its huge victory should imply. Mr Hatoyama must now apply the same innovative energy that galvanised the voters to usher in a new era in Japan's politics.