The nation on course to choose female prime minister in historic first

Over the last two decades, Japan has seen over ten leaders.

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

But why does Japan keep changing leaders? This is partly because of it being a "one-party democracy", explains Professor James Brown of Temple University in Japan.

The LDP's grip on the political landscape means the primary rivalry originates within the party, instead of from opposition groups.

"Therefore inside the LDP there are vicious struggles within various groups - they all desire their own clique to get the leadership position."

"So even though you could be chosen as leader, 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
• Internal factional rivalries drive power struggles
• The leadership role is frequently called a "cursed position"
• Political stability remains elusive despite financial power