German President Joachim Gauck embarked on a five-day trip to Japan on Monday, where he will hold talks with reigning Japanese Emperor Akihito, Crown Prince Naruhito and Prime Minister Shinzo Abe.

On the agenda are expected to be Donald Trump's election, as well as Japanese regional tensions with China and North Korea. The highlight of Gauck's trip will be a speech at the Waseda University in Tokyo on Wednesday.

Gauck and his partner, Daniela Schadt, will visit the capital Tokyo and the imperial city of Kyoto, as well as Nagasaki, which was wiped out during the final days of World War II, when the United States dropped an atomic bomb on the city.

This will be Gauck's first visit to Japan, but it underlines a strong relationship between the two countries - every German president has embarked on a state visit to Japan since WWII. The previous president, Christian Wulff, visited the country in October 2011.

Trump on the agenda

The transnational effect of Trump's US election victory looks set to dominate much of the diplomatic debate. 

In an interview with Japanese newspaper "Yomiuri Shimbun" ahead of his visit, Gauck warned against rising euroskeptic and populist sentiment. Gauck wrote that "these movements stir up resentment, serve nationalist ideals and pretend to easily be able to solve the problems of our time." 

Gauck added that watching the US presidential election campaign, and noticing how little facts and truth played a role, was "highly irritating." However, he said that the US remained a leading political, economic and military power. "I wish for Mr Trump to take on these responsibilities with great care," Gauck said. 

The president had previously told German weekly "Der Spiegel" two weeks before the election that Trump's "unpredictability" was a cause for concern. "We can't say what could be expected from a President Donald Trump," Gauck said, adding that for many Germans "this constitutes a problem."

"When I look at Washington, I am worried," Gauck said.

Trump had warned during the campaign that he would consider withdrawing US forces stationed in Japan unless Tokyo sharply raised its share of the deployment cost.

Coalition leaders agree on successor

The president's state visit coincides with Germany's ruling coalition agreeing to support the Social Democratic Foreign Minister Frank-Walter Steinmeier as the coalition's combined candidate for the next presidency. 

Gauck, Germany's 11th post-war president, announced in June that he would not be running for a second stint as head of state. The 76-year-old said he was worried about his ability to continue devoting enough energy to the job if he continued into his eighties.