Japan’s largest association of war-bereaved from the Battle of Peleliu, one of the islands of Palau, will disband next spring because its aging membership is shrinking, members said Saturday.

The association, based in Gunma Prefecture, will disband after making a trip to the tiny Pacific island roughly 1,000 km east of the Philippines to commemorate those who died in the fierce battle there.

The group’s membership now stands at 270, compared with about 1,400 in 2005.

Emperor Akihito and Empress Michiko are scheduled to start a two-day visit to Palau on April 8 to mark the 70th anniversary of the end of World War II.

The Battle of Peleliu claimed around 10,000 Japanese soldiers and 2,000 U.S. servicemen in 1944. Palau was under Japanese rule for about 30 years until the end of the war.

The decision to disband was made after the government’s three-day search for remains in the island’s caves wrapped up on Friday with the discovery of bones that appear to be the remains of six Japanese soldiers, welfare ministry officials said.

The ministry will send experts to the island as early as May to examine the bones, which will be brought back to Japan if confirmed to be Japanese.

The association was set up in 1965 and comprises survivors and families of soldiers from the Imperial Japanese Army’s 15th Infantry Regiment, which was holding Peleliu and its strategic airfield, it said.

The group has visited Palau 18 times to recover remains and clean the cemeteries, but most of the surviving members are now in their 70s or above.

Yoshitsugu Matsui, who was sent to Palau during the war, visited the island nation in 1990 as a member of the association and found dozens of skulls in a cave.

“There are more remains. I want to search for them, but it is tough for me to make a long trip,” the 93-year-old said.

Shigeru Tsukagoshi, the 85-year-old head of the association, said, “Although we will draw the curtain on the group when we visit Palau next spring, we will create an opportunity to talk about the war by gathering over the Bon summer vacation.”