HIGASHISHIRAKAWA, Japan (AP) — The former U.S. Marine knew the calligraphy-covered flag he took from a fallen Japanese soldier 73 years ago was more than a keepsake of World War II. It was a treasure that would fill a void for the dead man’s family. But Marvin Strombo did not know how deep that void was.

The flag he is to hand over to Sadao Yasue’s younger brother Tatsuo and his relatives Tuesday will be the first trace of their brother. The Japanese authorities only gave them a wooden box containing a few rocks, a substitution for the remains that have never been found.

Strombo, 93, who was part of an elite scout-sniper platoon fighting a 1944 battle on Saipan, spotted a dead Japanese soldier lying on the ground, with something white poking out from his jacket. He could tell it was “something special.” He initially hesitated, but took it because if he didn’t someone else would or it may get lost forever. He told the soldier he would return it to his family someday.

The flag’s white background is filled with signatures of 180 friends and neighbors in this tea-growing mountain village of Higashishirakawa, wishing Yasue’s safe return. “Good luck forever at the battlefield,” a message on it reads. Looking at the names and their handwriting, Yasue clearly recalls their faces and friendship with his brother.

“The flag will be our treasure,” Tatsuya Yasue, a younger brother of the fallen soldier, told the Associated Press at his 400-year-old house. The 89-year-old farmer says the return of the flag brings a closure to him and his brother.

“It’s like the war has finally ended and my brother can come out of the limbo,” he said.

Yasue last saw his older brother alive the day before he left for the South Pacific in 1943. Tatsuya and two siblings had a small send-off picnic for the oldest brother outside his military unit over sushi and Japanese sweet mochi, which became their last meal together. At the end of the meeting, his brother lowered his voice, asking Tetsuya to take good care of their parents, as he would be sent to the Pacific islands, harsh battlegrounds where chances of survival were low.

A year later, the wooden box containing the stones arrived. Months after the war ended, the authorities told Yasue his brother died somewhere in the Marianas on July 18, 1944, at age 25.

Strombo is the only person who can provide those answers. He can roughly show where he found Yasue’s body on the outskirts of Garapan and can tell the siblings that their brother likely died of a concussion from a mortar round. At least the flag and his story suggest Yasue died on the ground, which raises hopes of retrieving his remains.

The remains of nearly half of 2.4 million Japanese war-dead overseas have yet to be found 72 years after the World War II ended. It’s a pressing issue as the bereaved families reach old age and memories fade.

Allied troops frequently took the flags from the bodies of their enemies as souvenirs. But to the Japanese bereaved families, they have a much deeper meaning, especially those, like Yasue, who never learned how their loved ones died and never received remains. Japanese government has requested auction sites to stop trading wartime signed flags.

Strombo had the flag hung in a glass-fronted gun cabinet in his home in Montana for years, a topic of conversation for visitors. He was in the battles of Saipan, Tarawa and Tinian, which chipped away at Japan’s control of islands in the Pacific and paved the way for U.S. victory.

In 2012, he was connected to an Oregon-based nonprofit Obon Society that helps U.S. veterans and their descendants return Japanese flags to the families of fallen soldiers. The group’s research traced it to the tea-growing village of 2,300 people in central Japan by analyzing family names.