Japan set to elect female prime minister in landmark first

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

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

But why does the country keep changing prime ministers? It's due in part of it being a "single-party system", explains Prof James Brown of Temple University in Japan.

The Liberal Democratic Party's control on the political landscape means the main political competition comes from inside the party, rather than from external parties.

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

"Thus although you could be chosen as prime minister, as soon as you're in office, you have many individuals manoeuvring to try to get you out again."

Key Factors Behind Frequent Changes

• One-party dominance restricts outside challenges
• Internal factional rivalries fuel leadership contests
• The leadership role is frequently called a "cursed position"
• Political stability stays elusive despite economic strength