Japan has named Takeaki Matsumoto as the new Foreign Minister, after his predecessor quit at the weekend over a political donations scandal.
The 51-year-old was deputy foreign minister in Naoto Kan's government, and is a great great grandson of Japan's first prime minister.
His appointment comes as Mr Kan is struggling to get budget bills through parliament and hold on to his own job.
Japan is also embroiled in territorial disputes with China and Russia.
Mr Matsumoto replaces Seiji Maehara who stepped down on Sunday after just six months in the job, after he acknowledged accepting political donations from a foreign national - illegal in Japan if done intentionally.
His resignation added to the impression of a government in disarray, and prompted renewed opposition calls for Prime Minister Naoto Kan's resignation.
Mr Kan is struggling to pass bills through parliament to implement the trillion-dollar budget for the new financial year which begins next month.
Japan's government has acted swiftly to replace Mr Maehara.
Mr Matsumoto is a veteran lawmaker in the ruling Democratic Party of Japan, serving on several powerful committees before becoming deputy foreign minister.
Analysts say his policy views are pro-US, similar to his predecessor's.
Chief Cabinet Secretary Yukio Edano said Mr Matsumoto had been chosen for his "capability, knowledge and to ensure continuity of diplomacy".
His appointment comes at a time of strained relations between Japan and neighbouring countries.
On Tuesday, Japan lodged a formal protest after a Chinese helicopter flew close to one of its destroyer near a disputed gas field in the East China Sea.
It was the latest in a series of diplomatic battles over maritime territory, reflecting growing tension over the region's realignment of roles as China's economy and armed forces grow.
Relations between the two nations have been strained since a row last year over the arrest of a Chinese trawler captain near a disputed chain of islands, known in Japan as the Senkaku islands and in China as the Diaoyu islands.
Japan is also in a territorial dispute with Russia over the Kuril Islands in the Pacific Ocean.
The row over the islands, which are known as the Northern Territories in Japan, has stopped Tokyo and Moscow from signing a peace treaty since the end of World War II.
Japan also faces ongoing threats from nearby North Korea.