Japan's upper house has elected a president from outside the ruling Liberal Democratic Party (LDP) for the first time in more than 50 years.
Veteran lawmaker Satsuki Eda won the election unanimously
Lawmakers voted unanimously for Satsuki Eda of the Democratic Party of Japan (DPJ), who becomes the first opposition politician to hold the post.
The move follows the LDP's crushing defeat in July's upper house elections.
Its ruling coalition lost its majority, while the DPJ made huge gains and became the chamber's largest party.
Since the polls, Prime Minister Shinzo Abe has faced calls for his resignation, but says he intends to remain in office.
He has, however, pledged a Cabinet reshuffle, which is expected to take place later this month.
The 66-year-old new president, Satsuki Eda, is a veteran DPJ lawmaker. He told the chamber that Japan's political landscape had altered.
"The make-up of the upper house has drastically changed after the upper house elections and we are facing a political situation we have never faced before," he said.
"I think voters' expectations for the upper house are now extremely high."
Some analysts believe the new situation could lead to political deadlock.
The ruling coalition still controls the more powerful lower house, but the opposition could now block bills in the upper house, forcing the spotlight on potentially controversial issues.
One such issue is that of Japanese maritime support for US-led forces in Afghanistan.
Japanese naval vessels have been providing refuelling and other logistical support in the Indian Ocean.
Mr Abe says he needs the DPJ to work with him
The current mandate for the mission - which the DPJ opposes - is to expire on 1 November.
On Monday, speaking at a ceremony to commemorate the 62nd anniversary of the dropping of the atomic bomb on the city of Hiroshima, Mr Abe acknowledged that he faced a problem.
"I will strive to pass the laws in order to meet the expectations of the international community and contribute to it," he said.
"I want to discuss this thoroughly with people of the Democratic Party and seek their cooperation," the embattled premier told journalists.
Recent polls have indicated further falls in support for Mr Abe, who took office in September 2006.
A survey conducted by the Mainichi newspaper on 4/5 August showed support for him at 22%, a new low.
He has been hit by a series of ministerial scandals and a pensions crisis, which have led voters to question his leadership skills.