Japan set to choose female prime minister in landmark first

In the past twenty years, Japan has had more than 10 leaders.

In fact, a specialist likens assuming the country's top job to drinking from a "poisoned chalice".

However, what is the reason does the country keep changing leaders? It's due in part of it being a "one-party democracy", says Professor James Brown of Temple University Japan.

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

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

"Thus although you could be selected as leader, the moment you're in office, you have dozens of people scheming to try to remove you again."

Key Factors Behind Rapid Turnover

• One-party dominance restricts outside challenges
• Internal factional rivalries fuel leadership contests
• The leadership role is often described as a "poisoned chalice"
• Government continuity stays difficult to achieve despite financial power