Last held in Seoul in 2015, the three-way summit has regularly brought together the East Asian neighbours, but this week's gathering comes amid an unusual period of calm for relations often beset by territorial and historical disputes.
China, Japan and South Korea agreed on Wednesday to co-operate on ending North Korea's nuclear programme and promoting free trade, two hot-button issues challenging their region.
The agreements came at the first summit for the Northeast Asian neighbours after a hiatus of more than two years, bringing together Japanese Prime Minister Shinzo Abe, Chinese Premier Li Keqiang and South Korean President Moon Jae-in.
Abe said they discussed how they could get North Korea to give up its nuclear weapons, but he didn't provide any details. China and Japan, in particular, have differences over how best to achieve North Korea's nuclear disarmament.
TRT World's Reagan Des Vignes has more.
Looking for "peace and stability"
The meeting comes amid a flurry of developments on the Korean Peninsula. North Korean leader Kim Jong-un met Moon on April 27 and Chinese President Xi Jinping earlier this week, in a surprise visit to the Chinese coastal city of Dalian. US Secretary of State Mike Pompeo flew to Pyongyang, North Korea's capital, early on Wednesday to finalise details of a summit planned between President Donald Trump and Kim.
"We must lead the ongoing momentum toward complete denuclearisation of the Korean Peninsula and achieve peace and stability in Northeast Asia," Abe told a joint news conference in Tokyo.
Japanese Deputy Chief Cabinet Secretary Yasutoshi Nishimura said the three leaders also agreed to work toward two free trade agreements, a free trade pact among themselves and the proposed Regional Comprehensive Economic Partnership with Southeast Asian nations.
Trump has threatened all three countries with tariffs in a bid to seek trade concessions from them. His moves have raised fears of a trade war between the US and China.
Li, the No 2 official in China after President Xi Jinping, said earlier that free trade was a good way to promote a global economic recovery.
"We are willing to work with Japan and South Korea to jointly maintain regional stability and push forward the development of the three countries," he said before the meeting started.
The leaders also agreed to hold trilateral summits on a regular basis and set up a secretariat. The summits, which started in 2008, are supposed to be held annually, but Wednesday's was the first since November 2015.
Analysts say Japan is trying to showcase improved ties and co-operation with China and South Korea so its views will be represented in any negotiations with North Korea.
Abe reiterated Japan's position that it would normalise ties with North Korea only if the latter took concrete steps toward abandoning its nuclear and missile programmes and resolved the issue of Japanese abducted by North Korean agents.
Japan's leader was to hold talks separately with Moon and Li later on Wednesday. Japanese officials said they plan to propose a free and peaceful East China Sea, but do not plan to raise contentious issues such as South Korean "comfort women" forced to provide sex to Japan's wartime military.
Moon is to leave Japan after half a day. After that, Abe will host a dinner and lunch for Li and join him on the northern island of Hokkaido on the final day of his four-day Japan visit.
Japanese foreign ministry officials said they wanted to improve Japan's strained relations with China, with the eventual goal of realising a visit by Xi.
While Japan, China and South Korea are closely linked economically, anti-Japanese sentiment runs deep in China and South Korea because of territorial and historical disputes dating back to Japan's colonisation of the Korean Peninsula and invasion of China in the first half of the 20th century.