Japan set to elect woman prime minister in historic first

In the past twenty years, Japan has had over ten prime ministers.

Actually, one expert likens taking up the country's top job to drinking from a "cursed cup".

But why does the country frequently replace leaders? This is partly because of it being a "one-party democracy", says Prof James Brown of Temple University in Japan.

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

"Therefore inside the LDP there are intense conflicts within different factions - they all desire their own faction to get the leadership position."

"So even though you could be selected as prime minister, the moment you're in office, you have dozens of people scheming to try to remove you again."

Main Reasons Behind Rapid Turnover

• Single-party rule limits external competition
• Party infighting drive leadership contests
• The prime minister's position is often described as a "poisoned chalice"
• Political stability stays elusive despite financial power