The nation set to elect female prime minister in landmark first

In the past twenty years, Japan has seen more than 10 prime ministers.

Actually, one expert likens taking up the nation's top job to taking a "poisoned chalice".

But why does Japan keep changing prime ministers? It's due in part of it being a "one-party democracy", says Prof James Brown of Temple University Japan.

The LDP's grip on the country's politics means the main political competition comes from within the party, instead of from opposition groups.

"Therefore inside the LDP there are intense conflicts within various groups - they all want their own clique to get the top job."

"So even though you could be selected as leader, the moment you're in office, you have many individuals manoeuvring to try to get you out again."

Key Factors Behind Rapid Turnover

One-party dominance restricts outside challenges
Party infighting fuel power struggles
The leadership role is frequently called a "cursed position"
Political stability remains difficult to achieve despite financial power