Prime Minister Fumio Kishida said his “heart aches” over Japan’s colonial rule of the Korean Peninsula, speaking after a meeting Sunday with South Korean leader Yoon Suk-yeol in Seoul — the first such bilateral visit by a Japanese leader in more than 12 years — with the two hailing the speed of progress in their countries’ improving relationship.

The visit, which came on the heels of a March trip to Tokyo by Yoon, was largely focused on maintaining momentum for bettering ties after the relationship plummeted in 2018 to its lowest point in years over wartime history and other issues.

But it also saw the two leaders agree on a spate of issues, including the dispatch of South Korean experts to Japan on May 23 to conduct a scientific analysis as a part of “meaningful steps” to help the South Korean public better grasp Tokyo’s plan to release treated radioactive water into the sea from the crippled Fukushima No. 1 nuclear power plant.