The nation set to choose female prime minister in landmark first

In the past twenty years, the country has seen over ten prime ministers.

In fact, a specialist likens taking up the nation's highest office to taking a "poisoned chalice".

But why does the country frequently replace leaders? It's due in part of it being a "one-party democracy", explains Professor James Brown of Temple University Japan.

The LDP's grip on the country's politics means the main political competition originates within the party, rather than from opposition groups.

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

"So even though you might be selected as leader, the moment you're in office, you have dozens of people manoeuvring to try to remove you again."

Key Factors Behind Rapid Turnover

• Single-party rule restricts external competition
• Party infighting fuel leadership contests
• The prime minister's position is often described as a "poisoned chalice"
• Government continuity stays difficult to achieve despite economic strength