A film about a member of the Nazi party who saved thousands of Chinese during the massacre in Nanjing recently opened in Germany. The BBC's Zoe Murphy looks at the possible impact this unlikely hero's story may have on Sino-Japanese relations.
On Christmas Eve in 1937, German businessman John Rabe visited the mortuary in China's then capital, Nanjing.
He later described in his diary the charred body of a civilian man whose eyes had been gouged out, and a boy of perhaps seven, whose corpse was punctured with bayonet wounds.
John Rabe remains a hero in China but his story is little known elsewhere
"I wanted to see these atrocities with my own eyes, so that I can speak as an eyewitness later," he wrote. "A man cannot be silent about this kind of cruelty!"
The Second Sino-Japanese War was raging.
Japanese troops had stormed the capital, carrying out mass executions and raping tens of thousands of local women and girls, in a six-week orgy of violence that became known as the Rape of Nanjing.
Risking his life, Rabe remained in China and, along with a handful of Westerners, set up a "safety zone" in Nanjing that is thought to have prevented the massacre of more than 200,000 Chinese during one of the bloodiest episodes of the Japanese invasion.
As Germany and Japan were allies, Rabe used his Nazi party membership to do all he could to protect civilians in the zone - including sheltering 650 refugees in his own house and garden.
Japanese soldiers used live Chinese prisoners for bayonet practice
With a flash of his swastika armband and through sheer force of personality, he intervened in acts of looting and attempted rape by the Japanese troops.
The diaries of this unlikely and unsung hero only became public knowledge in the late 1990s, when they were published in Germany. They have now been made into a film, simply titled John Rabe.
The biopic, which premiered recently in Germany, may stoke historical tensions between Beijing and Tokyo. But it is hoped that Rabe's story may renew debate and ultimately help heal old wounds.
The events of 1937 have left enormous psychological scars in China, and the Chinese believe that Japan has not done enough to atone for its militarist past.
China says 300,000 people were killed during the assault on Nanjing. But much to the anger of Beijing, some conservative Japanese politicians and academics have said such figures are exaggerated. Some even deny that a massacre ever took place.
Such declarations also frustrate mainstream historians in Japan and further afield.
William Kirby, head of the Fairbank Center for Chinese Studies at Harvard University, says the exact death toll is not the main issue.
"What you have is a great massacre of a civilian population that goes on for weeks
Nanjing is surrendered but the Japanese proceed to terrorise the inhabitants. These facts are incontrovertible."
Coming to light nearly 60 years after the event, he says that John Rabe's diaries are a powerful new document detailing what happened day-by-day.
Mr Kirby says that Rabe had "no anti-Japanese axe to grind" at the outset.
"He saw the Japanese as a normal army and initially resisted the stories of wrongdoing - he was a neutral outsider."
During the conflict, Rabe wrote: "Last night up to 1,000 women and girls are said to have been raped... If husbands or brothers intervene, they're shot.
"What you hear and see on all sides is the brutality and bestiality of the Japanese soldiery."
The film's director Florian Gallenberger says it was by staying true to the events as described by Rabe that the film achieved neutrality.
"At the beginning of the conflict I think [Rabe] has great trust in the Japanese as German allies to behave in a disciplined and fair way - but when it turns out otherwise he is shocked. He feels it is his responsibility to act."
He says Rabe's courage was fuelled by his sense of morality, rather than any political conviction.
The events of 1937 have left deep psychological scars in China
As bombs rained down, Rabe wrote: "Anyone who has ever... held a trembling Chinese child in each hand through the long hours of an air raid can understand what I feel."
At one point, he covered a shelter with a huge swastika flag, which he described as being considered "especially bombproof".
After living in China for 30 years, Rabe had a naive image of Germany's National Socialism as a humanistic workers' movement, says Mr Gallenberger.
Rabe even wrote to Adolf Hitler asking for his intervention in the violence, as he believed the Nazi leader would not have condoned Japan's actions.
'Hard to watch'
The passage of time has allowed Germany to review its own wartime actions, notably the Nazi genocide of some six million European Jews during World War II.
Now with historical distance, the 37-year-old director hopes the film will trigger a new dialogue and help Japan also come to terms with its own past.
"After such a long time, there should be a way of dealing differently with the responsibility they have, rather than trying to avoid it or make it disappear," he says.
Rabe's house in Nanjing is now a museum and centre for peace studies
John Rabe is expected to be widely viewed in China after it premieres at the Shanghai Film Festival in June. But it is unclear whether the film will be released in Japanese cinemas.
The film's producers hope that the involvement of Japanese star Teruyuki Kagawa will prevent the film from being silenced there.
Teruyuki Kagawa plays the emperor's relative, Prince Asaka, who was the top ranking Japanese officer in Nanjing at the height of the atrocities.
During the Tokyo War Crimes Tribunal in 1946, Prince Asaka denied any massacre of Chinese and said he had never received any complaint about his soldiers' conduct.
Controversially, the film speculates on his involvement in the decision-making process.
Teruyuki Kagawa says: "When faced with this film, many people will be shocked [to learn] the Japanese carried out such cruel acts.
"I think Japanese people will find the two hours very hard [to watch]."