The nation set to elect female prime minister in landmark first

In the past twenty years, the country has seen more than 10 leaders.

Actually, one expert compares assuming the nation's top job to taking a "cursed cup".

However, what is the reason does the country keep changing prime ministers? This is partly because of it being a "single-party system", says Prof James Brown of Temple University 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.

"So within the LDP there are intense conflicts within different factions - they all want their own clique to secure the leadership position."

"Thus although you might be selected as prime minister, the moment you're in office, you have dozens of people manoeuvring to try to remove you again."

Main Reasons Behind Rapid Turnover

• Single-party rule limits outside challenges
• Party infighting drive leadership contests
• The leadership role is frequently called a "cursed position"
• Political stability stays elusive despite economic strength