The nation set to choose woman prime minister in landmark first

Over the last two decades, the country has seen over ten prime ministers.

In fact, a specialist compares taking up the country's highest office to drinking from a "cursed cup".

But why does Japan frequently replace prime ministers? It's due in part of it being a "single-party system", says Prof James Brown of Temple University Japan.

The LDP's grip on the political landscape means the primary rivalry comes from within the party, rather than from external parties.

"Therefore inside the LDP there are intense conflicts within different factions - they all want their own clique to secure the leadership position."

"Thus although you might be selected as leader, the moment you're in office, you have dozens of people manoeuvring to try to get you out again."

Main Reasons Behind Rapid Turnover

• Single-party rule limits outside challenges
• Party infighting fuel power struggles
• The leadership role is often described as a "cursed position"
• Government continuity remains difficult to achieve despite financial power