Chinese President Xi Jinping has met Japanese Prime Minister Shinzo Abe at a time of warming ties between the two nations.
Relations have historically been strained, but concerns over US trade policy and North Korea's nuclear programme have shifted them closer.
The two leaders met on the sidelines of the forthcoming G20 summit in Japan.
"I want to open up a new age of Japan-China relations hand in hand with President Xi," Mr Abe told reporters.
The pair agreed to work together to promote "free and fair trade" following a "very frank exchange", a Japanese official said.
It is the first official visit Mr Xi has made to Japan since becoming president in 2013. At the outset of their talks on Thursday, Mr Abe invited him to return on a state visit next year.
"Around the time of the cherry blossoms next spring, I would like to welcome President Xi as a state guest to Japan," he said. "[I] hope to further elevate ties to the next level."
What did the leaders discuss?
Japan and China are by far Asia's largest economies and the talks on Thursday focused strongly on business.
Last year, the two sides signed a deal to maintain annual dialogue and to co-operate on innovation. This time around, officials say, they pledged to develop a "free and fair trading system" in a "complicated" global economic landscape.
Another topic on the schedule would probably have been North Korea. While China is North Korea's biggest trading partner, both Tokyo and Beijing want it to abandon its nuclear programme.
Mr Abe has only very limited leverage on the matter and will try to sway both the US and China to keep Tokyo's interests in mind in any negotiations.
The G20 summit will begin on Saturday, but the main meeting is likely to be overshadowed by the many bilateral talks that are set to happen on the sidelines.
For example, Mr Xi will meet President Trump as China and the US try to resolve their trade dispute.
Do Japan and China get along?
In the past, relations have been tense. While the two countries do have close trade ties, politically things have been much more fragile.
Japan's World War Two occupation of parts of China remains a very emotional issue. There are also several ongoing territorial disputes between Tokyo and Beijing.
But tensions with Washington over its protectionist trade policy have driven Japan and China into an unlikely friendship.
In 2018, Mr Abe hailed his high-profile visit to Beijing as an historic turning point. Both leaders have since promised to establish positive, constructive, relations.