They felt nervous as they believed their treatment was too good. In Siberia, where they had been kept from 1945 to 1950, many were in labor camps.
"In Siberia the food was not enough for one day's work. The weather was deadly cold. If you didn't eat well you die," former military policeman Masahito Niguchi said in the documentary.
In Fushun, their heaviest work was usually washing their clothes or cleaning their rooms. With time to kill, they played Weiqi and Mahjong.
They each received about 250 grams of tobacco a month if they wanted it, or a box of cigarettes if they were senior officers. They had one hot bath a week, a haircut each month, and enjoyed sports game every spring and fall.
"The center had medical facilities. We recorded their health status, treated them if necessary, fixed teeth and gave them spectacles and artificial limbs," said former chief nurse Zhao Yuying.
Jin Yuan said in his memoirs that the center "combined humanitarian education with criticism of militarism" to transform the criminals.
News about the Korean War caused much excitement. At first most of the prisoners didn't believe the Chinese army could beat the Americans, their conquerors in World War Two.
"When we heard the Chinese army was winning battles, we started to wonder what made China so powerful," said Yasutada Nanba, from the 39th Division.
The authorities opened a library and encouraged the prisoners to study. Koichi Okawara joined a group of 22 members to study Lenin's socialism in a storage room. "The Chinese instructor would ask how my study was going," Okawara said.
Ichiro Koyama said his group came from different education backgrounds. "The Chinese instructor didn't teach us. One of my group mates was a Tokyo University philosophy graduate. He taught us Das Kapital by Karl Marx."
Fujita Shigeru also learnt something. He was particularly interested in economics. "The Japanese history I was taught in my childhood raised many questions about economics," he said. He learned that Japan had invaded China to ease its economic crisis, then grabbed China's resources and controlled its market.
"Shigeru once watched a Japanese movie in the library called 'Children of Mixed Blood', which told the story about Japanese children whose fathers were American soldiers. When the children were mocked because of their different skin color, Shigeru cried," said Cui Renjie.
Cui also recalled that after 1954, the inmates could write home to their families. Shigeru's wife wrote back to tell him his older sister's family had died in the atomic bomb blast at Hiroshima.
"Shigeru lost the pride in his eyes, and shaved his thick moustache," Cui said.
However, it was just the beginning. "We knew the war was an invasion. But once you are involved, it is difficult to admit your own crimes," said Tsuyoshi Ebato.
The staff asked them to talk about their own lives and took them back to the scenes of their crimes.
One of the places they visited was Pingding Mountain, where Japanese troops slaughtered more than 3,000 civilians. When sole survivor Fang Surong told her story, they knelt and wept in front of her.
Gradually they started to talk about what they had done during the war."I said we should discuss it in groups of army, police and military police. That's the way we began," said Ichiro Koyama in the NHK documentary.
"You can't hide everything forever. We were not thinking about any possible punishment we would get; we just wanted to confess as humans," Ichiro said.
Saburo Shimamura, a secret police officer who was close to Shigeru, said in his book "War Criminal Returning from China" that in Fushun he always dreamed about what he had done during the war.
"At least 6,000 Chinese were killed by me or on my order, maybe more than that..."
One morning, Saburo passed a note to Shigeru: "I feel ashamed. I have changed my mind and now am ready to write about my war crimes."
"If you write, then I will do so," Shigeru wrote back.
Documents released by China's State Archives Administration on Aug. 16, 2014, show Shigeru's 105-page confession detailed the murders of hundreds of Chinese civilians and captives from 1938 to 1945.
"May 21, 1944: shot dead 12 Chinese (including one woman) in Luoyang, Henan," it read.
"March 27, 1945: massacred all inhabitants of about 50 households in a village along the Dengxian County-Laohekou road, 200 meters north of Zhulinqiao, killing the elderly, women, children ... and other inhabitants; used gas shells during the attack in Maqushan the same day."
His confession shocked his fellow inmates and more of them followed.
In June 1956, Fujita Shigeru and the other war criminals were tried at China's special military court in Shenyang. Shigeru was sentenced to 18 years in jail and 44 other senior officers were jailed from 8 to 20 years. The others were exempted from prosecution and returned to Japan. All of them had pleaded guilty and asked forgiveness from the Chinese people.
"When I made a public confession of everything, the man I was before had gone. I felt sad, but relieved, and tears rolled down my face," said Zhennao Kimi in the NHK documentary.
Shigeru returned to Japan in February 1963. He was elected chairman of the Liaison Council for Repatriates from China, a peace group organized by the war criminals once held in Fushun.
The organization promoted peace and anti-militarism with speeches and demonstrations. He also led five friendship delegations to China to facilitate Sino-Japan relations.
He died in 1980. According to Jin Yuan's memoirs, Shigeru asked his family on his death bed to dress him in a Zhongshan suit (Sun Yat-sen's uniform), a gift from the late Chinese Premier Zhou Enlai.
The Liaison Council for Repatriates from China disbanded in 2002 due to dwindling numbers.
The children of its members and some Japanese peace activists established the Association to Carry on the Miracle in Fushun, to commemorate what happened there.
