This would be a very interesting summit if it ever happened. I wonder if they would do it if China said North Korea has to attend as well?:
South Korean President Yoon Suk Yeol (L) and Japanese Prime Minister Fumio Kishida talk during a visit to the Raj Ghat memorial in New Delhi on Sept. 10, 2023. (Pool photo) (Yonhap)
South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida agreed Sunday to work toward realizing a trilateral summit with China, the presidential office said.
The two held talks on the margins of a Group of 20 summit in New Delhi, expressing their pleasure at meeting a total of six times since March, when Yoon traveled to Tokyo to mend bilateral relations badly frayed over historical disputes.
“The president said the two countries should continue active meetings in the second half of the year and smoothly implement the process to hold a South Korea-Japan-China summit,” the presidential office said in a press release. “Prime Minister Kishida said he would actively respond.”
Yonhap
You can read more at the link.