GIFU, Japan (Kyodo) -- A Buddhist priest who was drafted by the Japanese military and endured horrendous conditions, including witnessing the deaths of many compatriots, while detained in a Soviet internment camp near the end of World War II died recently at 99 years of age.

After being repatriated following the war, Shudo Yokoyama did not speak about this dark period of his life for several decades before deciding to open up when he saw the anguish of a Japanese woman who had lost her detainee husband in the war.

But he was later stunned to learn what had happened in an earlier conflict -- a "forgotten war" that ran from 1918-1922, in which the Japanese military occupied Siberian cities and towns in support of forces resisting communist Red Army combatants in the Russian Civil War.

Yokoyama, who spent more than 35 years traveling to mourn the victims of both incidents and keep their memories alive, died in August, having remained faithful to his cause.

Born in the town of Ibigawa in Gifu Prefecture, central Japan, Yokoyama went to Manchuria in 1943, a region in present-day northeast China, when he was 18 years old. He worked as a Buddhist monk in the province of Jilin before being conscripted at the age of 20.

He was sent to a forced labor camp in Komsomolsk, deep in Siberia, after being captured by the Soviets who launched a massive invasion of Manchuria toward the end of the war.

"Sometimes the temperature would drop to minus 60 C. Even though my body would become as hard as rock, I had no choice but to work," Yokoyama said before his death.

Food in the camp was substandard and always scarce, and many of his friends died.

Close to 600,000 Japanese soldiers are believed to have been held in Soviet labor camps in the wake of Japan's defeat in the war. They were interned for up to 11 years, with about 55,000 dying as a result of the work they were forced to do, the severe living conditions and malnutrition.

Yokoyama returned to his hometown in 1947 after about two years of internment. He taught at a middle school and elsewhere but never spoke of his internment. Being a time of rapid change and high economic growth, Yokoyama said, "My internment experiences were so far removed from everyday life, I had no desire to reveal them."

But in 1983, after ending his teaching career, he returned to Siberia at the age of 58 as a member of a now-defunct national council working for the compensation of Japanese detainees.

When a memorial service was conducted at a Japanese cemetery in Khabarovsk, the largest city in Russia's Far East, he was heartbroken by the sight of the wife of a dead Japanese detainee crying while clinging to her husband's grave.

From then on, while recalling the faces of his fallen comrades, Yokoyama determined he would do everything in his power as a priest to mourn the victims of the war.

Then in 1991, he visited the Russian village of Ivanovka on part of a trip to search for burial sites of detainees. There, for the first time, he learned of the tragedy of the Imperial Japanese Army's destruction of the village that killed some 300 residents in March 1919 during what was termed the Siberian intervention.

After the October Revolution of 1917 brought the Soviet regime to power, Japan, as part of a coalition of Allied powers, intervened militarily the following year by dispatching an expeditionary force to Siberia, ostensibly to support groups fighting against the Bolsheviks.

The Japanese soldiers advanced to as far as Irkutsk on the western shore of Lake Baikal, but it was unable to extend control outside railroad lines and cities, and it faced guerrilla attacks launched by resistance forces.

After receiving criticism for continuing to station troops in Siberia after other countries, including the United States, withdrew, Japan left Siberia in 1922 but remained in northern Sakhalin until 1925, targeting oil and coal resources.

Although it is estimated that more than 70,000 Japanese troops were deployed -- by far the most among the Allied contingent -- with more than 3,000 killed during a roughly seven-year stretch, the actual situation is murkier and not well explored even today.

"I was embarrassed that I knew nothing about this tragedy," Yokoyama said, referring to the Ivanovka village slaughter. The council collected donations to build monuments dedicated to the victims of both sides of the Siberian conflict.

After the dissolution of the council, Yokoyama established a now defunct nonprofit association for promoting friendship and goodwill with Russia and continued grassroots exchanges.

In 2018, on the 100th anniversary of the Siberian intervention, a joint Japan-Russia memorial service was held with the Russian Orthodox Church, offering sutra readings and a pledge to pass on the memories of those lost.

Not all locals appreciated the presence of Japanese cemeteries in their homeland. Nonetheless, residents welcomed Yokoyama with cookies and other homemade baked treats. Due to old age, 2019 was his final Siberia visit.

He always cherished the words of the locals who once told him, "We breathe the same air under the same sky and live on the same Earth. I hope more people in Russia and Japan will interact with each other."

In June, three months ahead of his 100th birthday, a celebration was held at Shozenji Temple in Ibigawa where Yokoyama had served as chief priest. There, once again, he spoke of the origins of his peace activities.

"I am here today because of my experience of Soviet internment," he said. A stone monument inscribed with the words, "A gravestone: remembering the tragedies of Siberia" stands in the temple precinct to convey this spirit.

(By Kazutaka Hinata)