TOKYO (AFP) — Japan's leadership race kicked off Thursday with a record nine candidates including the surfing son of a former prime minister and an arch-nationalist vying to be the first woman premier.

Whoever wins the Liberal Democratic Party (LDP) leadership vote on 27 September will succeed unpopular Prime Minister Fumio Kishida, whose three-year term was tarnished by scandals and unease over rising prices.

The contest comes as Japan beefs up defense spending and cooperation with fellow United States allies to counter China and as the spluttering world-number-four economy struggles with a slow-burn demographic crisis.

The conservative LDP has governed almost uninterrupted for decades and holds a majority in parliament, meaning the winner is essentially guaranteed to become premier.