Yoshio Shinozuka sits on the wooden steps of an old Buddhist temple just down the road from his home. It is where he will be buried.

Surrounded by pine trees and rice paddies, the temple is quiet save for the incessant buzzing of cicadas.

Frail and fast approaching his 83rd birthday, he points to a small cemetery guarded by a statue of the Goddess of Mercy that will be his final resting place.

"I've already chosen the plot," he says.

Shinozuka has had a lot of time to reflect on his youth, and his memories of those days are crystal clear. But they are laced with poison.

A member of Japan's Unit 731 in Northeast China in the 1930s and '40s, Shinozuka belonged to perhaps the most advanced biological weapons operation of its time.

As a teenager, he participated in atrocities -- vivisections and other experiments on humans -- that for millions of Chinese epitomize Japan's imperial rampage through Asia.

Conservative estimates place the number of the unit's victims in the thousands -- as many as 250,000, some historians believe.

For many years, Japan's government denied Unit 731 existed.

In a landmark ruling in 2002, a Japanese court finally acknowledged the unit's operations caused "immense" suffering and were "clearly inhumane." But like previous courts, it said the government had no legal obligation to atone to the victims.

As far as many Asians are concerned, Japan has never faced up to its past. World War II remains an open wound deeply affecting its relations with its neighbours.

Shinozuka, however, has devoted himself to making amends.

He testified on behalf of his Chinese victims. He has written a book for schoolchildren.

In 1998, he tried to speak at peace conferences in the United States and Canada -- but immigration inspectors turned him away as a war criminal. He accepts that label.

"It took me a long time to get beyond the excuse that I was just following orders," he said.

"I was doing what I was told. And I might very well have been killed had I disobeyed. But what we did was so terrible that I should have refused, even if that meant my own death.

"But I didn't do that. And I will never be forgiven."

In February 1939, as Japan's war machine was devouring China, a recruiter came to Shinozuka's rural high school, dressed in an army aviator's uniform and promising a bright future for those who signed up.

There would be college scholarships and possible careers in medicine or aviation, lots of travel, the satisfaction of serving the emperor.

"We were all impressed," Shinozuka recalls. "It seemed like quite an opportunity."

Shinozuka aced the examination. "I think everybody passed that test," he said. "It was very easy."

Bio-warfare unit recruit

He was 15 years old. Two months later, he was ordered to join Unit 731 of the Epidemic Prevention and Water Purification Department of the Kwantung Army and was shipped off to its sprawling headquarters in the city of Pingfan, just outside Harbin in Japan-controlled Northeast China.

"The idea was that we would be responsible for providing our soldiers with safe drinking water," he said.

As a civilian with the unit's youth corps, Shinozuka spent most of his time in a classroom learning about basic medicine, sanitation and the spread of germs.

In the spring of 1940, he was given a more hands-on mission.

"Our unit was raising fleas and infecting them with the plague," he said. "My job was to see that they had live rats to grow on."

It was a simple operation -- the rats and their fleas, along with grains of wheat, were kept in small cages in a dark room. When a rat died, the fleas would naturally move away from its corpse and were then corralled by carefully placed red lights through a bathtub into a glass cylinder attached to the drain.

"What happened to the fleas next wasn't our concern," he said.

But soon after Shinozuka got his new assignment, Chinese people began dying of the plague.

According to documents filed by a group of Chinese victims with the Tokyo District Court in the 2002 compensation suit, Japanese military planes on the morning of October 4, 1940, dropped wheat with plague-infected fleas over the city of Quxian (today's Quzhou in East China's Zhejiang Province).

Despite intense efforts by townspeople to burn the infected materials, at least two dozen deaths from bubonic plague were reported there by year's end.

A railworker infected by the Quxian strain then spread the disease to Yiwu in Zhejiang, where more than 300 died. Hundreds more plague deaths followed in nearby areas.

In November 1941, Unit 731 aircraft also dropped cotton, grain and other flea-infested materials on the town of Changde, in Central China's Hunan Province, causing two outbreaks -- the second beginning the following spring when infected rats became active after surviving the winter. Overall, as many as 7,643 died.

"I never asked why we did what we did," Shinozuka said. "Nobody did. We weren't given any time to think about what we were doing. And there was an unspoken rule to hear no evil, see no evil, speak no evil. But there is no doubt in my mind that what the Chinese say is true."

Shinozuka's studies continued. Back in the classroom, he learned about the mass production of typhus, cholera, anthrax and dysentery.

Then, in 1942, he was given another task -- preparing plague-infected people to be cut up alive.

Cruel and inhumane experiments

Prisoners were infected so that the unit could study the progress and potency of their biological weapons.

Samples removed from the prisoners were used to produce more bacteria.

"The first time, my legs were shaking so badly I could hardly stand up," Shinozuka said.

He knew the person on the operating table.

"I'd seen him a few times," he said. "He seemed like an intellectual. He wasn't even 30. But by the time he was brought in to the dissection room, he was so black with the plague that he looked like a different person. He was clearly on the verge of death."

In a tiled operating room, Shinozuka cleaned the victim with a scrubbing brush, front then back, then dried him off.

Another man used a stethoscope to make sure the victim was still alive and then assisted a third man, who quickly but methodically cut the victim open and removed his organs.

"We were told that it was crucial to extract the specimens before putrefaction had time to set in and contaminate our research," Shinozuka said.

"The room didn't have a clock, but I guess the operations took about four hours. I will never forget the feeling of being there."

Shinozuka personally participated in three more vivisections.

"We called the victims 'logs,'" he said. "We didn't want to think of them as people. We didn't want to admit that we were taking lives. So we convinced ourselves that what we were doing was like cutting down a tree. When you see someone in that state, you just can't move. Your mind goes blank. The fear is overwhelming."

Shinozuka was now 20 years old.

The next year, he was formally drafted into the army.

When the war ended in August 1945, Shinozuka was a lance corporal with a medical unit in Northeast China.

Separated from his superiors in the chaos of defeat, he was caught up in the Chinese civil war and imprisoned for a year by the People's Liberation Army under the leadership of the Communist Party of China.

When he got out, many of his countrymen had been repatriated. Alone and forgotten, he had nowhere to go.

"But the People's Liberation Army took me in," he said. "They treated me well, and I enjoyed serving with them."

After six years, his past with Unit 731 was discovered. He was sent to a re-education camp, where he remained until 1956.

Oddly enough, he said, he has fond memories of his detention there.

"The camp was built by the Japanese, and it was quite spacious and comfortable," he said.

"We ate better than the guards. They showed us movies and played music for us. We were allowed to play sports. It was much better than life in Pingfan."

In the camp, Shinozuka began to reflect on his actions with Unit 731.

"I began to be a human again," he said. "Had they been harsh with me, I might have gone into my shell. But they treated me as a person, and I had to think of them as people. I began to think of the victims as people, too."

Shinozuka said that although he initially lied about his Unit 731 activities, saying he was researching new vaccines, he gradually began confessing the truth.

Gratitude to the Chinese

"I don't think they had much use for what I was telling them," he said. "But they sent me home with a pardon. I was never charged."

Every May, a couple of dozen of Shinozuka's comrades from the re-education camp join him at the temple in Yokaichiba, a village about 100 kilometres (60 miles) east of Tokyo.

Near the Shinozuka family plot, they have built a simple stone monument to Japan's Chinese victims.

"We express our endless gratitude to the Chinese people, and our deepest apologies," the monument says.

Of the 1,109 prisoners returned from the camp in 1956, few if any were Unit 731 members. Those unit leaders who made it back to Japan were spared prosecution in exchange for turning over information to the United States.

One rose to prominence in Japan's pharmaceutical industry. Others went to work for the Health Ministry.

Back in Japan, but with no home to return to, Shinozuka managed to get a job with the local government office and kept it until his retirement.

Though he often wanted to tell his story, "no one wanted to hear what I was saying," he said.

"The Japanese prefer to think of themselves as victims in the war. Even the peace movement people told me that talking about Japan's role as an aggressor wasn't constructive.

"But I couldn't let this piece of history remain in the dark."

In 1997, the same year he raised the monument, he testified on behalf of the 180 Chinese suing Japan for compensation.

The court denied them compensation and they began an appeal on September 2.

Health permitting, Shinozuka intends to be at some of the hearings.

In recent years he has visited China often and has been back to Unit 731's former headquarters. The site is now a museum.

"The Chinese have been very generous with me," he said. "They tell me that I, too, am a victim."

(China Daily September 20, 2004)