By Sakura Murakami and John Geddie TOKYO (Reuters) -A leadership contest in Japan's ruling party to determine who will take over as prime minister headed to a run-off on Friday, putting a candidate seeking to become Japan's first female premier against a veteran making his fifth leadership bid.

A seasoned defence geek and a nationalist who would be Japan's first woman prime minister will go head-to-head in the final round of a ruling party leadership vote on Friday,

Frequent government changes make it difficult for Japanese leaders to tackle long-term policy goals or develop trusted relations with other leaders. Japan’s diplomatic and security policies, though, will continue to be based on its key alliance with the United States.