Japan set to elect woman prime minister in historic first

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

In fact, one expert compares taking up the country's highest office to drinking from a "cursed cup".

But why does Japan keep changing leaders? It's due in part of it being a "one-party democracy", says Professor James Brown of Temple University Japan.

The LDP's grip on the country's politics means the primary rivalry originates inside the party, instead of from opposition groups.

"Therefore inside the LDP there are intense conflicts within different factions - they all desire their own faction to secure 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 Frequent Changes

• Single-party rule restricts outside challenges
• Internal factional rivalries fuel power struggles
• The leadership role is frequently called a "poisoned chalice"
• Government continuity stays elusive despite financial power