ð Share this article Japan set to choose female prime minister in historic first In the past twenty years, Japan has had over ten leaders. Actually, a specialist compares taking up the nation's top job to drinking from a "poisoned chalice". But why does the country keep changing prime ministers? It's due in part of it being a "one-party democracy", says Prof James Brown of Temple University in Japan. The LDP's grip on the country's politics means the primary rivalry originates within the party, instead of from opposition groups. "So within the LDP there are vicious struggles within various groups - they all want their own faction to get the leadership position." "So even though you could be chosen as leader, as soon as you're in office, you have dozens of people manoeuvring to try to get you out again." Main Reasons Behind Frequent Changes One-party dominance restricts external competition Party infighting fuel leadership contests The prime minister's position is frequently called a "poisoned chalice" Political stability stays elusive despite economic strength