The island nation of Palau is preparing for a visit from Japan’s Emperor Akihito next week with an unusual and grim task: It’s investigating long-sealed caves on the island of Peleliu to look for the remains of Japanese soldiers from World War II. The remains of six soldiers have been discovered so far, but that’s just the start. The Australian Broadcasting Corporation reports they were found in one of about 200 sealed caves on Peleliu. An estimated 10,000 Japanese men were killed in a weeks-long battle with US troops during the war, and the bodies of 2,600 of them were never found. The Japanese used a network of caves and tunnels during the 1944 fighting, recounts the Telegraph, and largely “staged their defense” from within the caves. About 1,600 American troops were killed, but the US military blew up many of the caves (essentially sealing the Japanese within) and eventually gained control. The six newly found bodies were found in the vicinity of an anti-tank gun, and “it’s my understanding that those [bodies] were the crew, perhaps the officer and his men that were manning that gun,” says one of the search officials. “A number of US soldiers died in that vicinity as well.” The task is painstaking because searchers need to guard against booby traps or the detonation of old munitions. An interesting side note from the Telegraph: Some 35 Japanese soldiers who had been hiding in the caves surrendered in April 1947—more than a year after the war’s end.