Pictures under occupation
A Japanese woman in a kimono is seen taking a walk with a Chinese friend in north China in 1939. On the wall behind them is the flag of the puppet regime and a slogan calling for Sino-Japanese unity.
But not all the photos serve such a clear propaganda purpose. Many are simple snapshots of daily life.
In Northern China in the 1930s, not many locals could afford cameras. These photographs were taken by the occupying Japanese.
The second Sino-Japanese war started in 1937 after the two countries clashed near the Marco Polo Bridge.
As Japan occupied more and more territory, it established the North China Railway Company in collaboration with the local puppet regime.
The company hired photographers to take tens of thousands of images of life in occupied China. The aim was to create an illusion of harmony for public consumption back home in Japan.
Of course, the picture was incomplete. Due to censorship and restricted access, the photographers didn't document the harsher realities of the occupation.
Hidden from sight
After the war, the pictures were quietly put into storage at Kyoto University. Only a handful of people knew about them, until their existence was revealed to the public in 2016.
The collection is one of the world's largest stockpiles of photos shot under the Japanese occupation.
Though many Chinese people see the images in a negative light, they are an important historical asset.
This photo shot in Beijing shows Chongwenmen, a gate in the southeast of the city that dated back to the 15th century, but which was torn down in the 1960s.
The images capture places and customs that are now being lost to modernization.
They were made public in February as the "North China Railway Archive." One of the university's China experts, Toshihiko Kishi, was key to the online publication.
It took him and his colleagues eight years to raise funds to run the project. In the introduction to the archive, it is emphasized that the pictures are a byproduct of Japan's invasion of China.
Backlash in China
The publication immediately caused an online sensation in China, but not in the way Kishi and his colleagues had hoped.
A tag on Weibo, a Chinese microblogging platform, describing it as "pictures of Japan's aggression in China" received 420 million page views.
And the comments were mostly negative.
"They released the pictures because they are proud of their history of conquest!"
"These pictures have been selected for whitewashing. The bloody ones are hidden."
Kishi and his colleagues were shocked at first, but they understand that many Chinese people feel the same way about the history of the Japanese invasion.
Self-censorship a factor
NHK approached several Chinese academics, all of whom acknowledged the value of the archive. However, all refused to be interviewed on camera for fear of becoming the target of an online backlash.
And they have good reason to worry. The words "Japan" and "history" are still a toxic combination in China that can easily stir up public outrage.
Professor Mao Danqing of Kobe International University is concerned about this trend. He has been involved in cultural exchanges between Japan and China for many years.
From 2011 to 2015, Mao was the chief editorial writer at a magazine called "it is JAPAN." Published in China, it covers a wide range of topics related to Japan.
But when he tried to write about the dark past of the two countries, he ran into resistance.
In 2014, Mao was prevented from publishing a feature marking the 120th anniversary of the first Sino-Japanese war.
He says the publisher spiked his story to avoid causing trouble. Politics and history are a minefield for publishers in China.
"Even the scholars who appreciate the true value of this archive may hesitate because of the social climate surrounding freedom of expression in today's China," says Mao. "There's not that much room for free speech, so many people avoid speaking out."
Bridging the gap
Despite the online backlash, the North China Railway Archive has produced positive results. An academic from China contacted Kishi about some of the photos.
This scholar said people are aware of less than 1 percent of the true value of the archive. Because there are so few records of 1930s China, many of the pictures may be the only proof of vanished cultural events and architecture.
He asked Kishi for copies of photos including one of a bridge at the Old Summer Palace in Beijing. The palace was destroyed in 1860 by the British and French military, but the bridge remained until the 1950s.
Kishi also received offers from at least three Chinese groups to hold exhibitions of the archive in China.
Kishi's dream is to conduct field research with Chinese scholars at the spots where the pictures were taken.
Many academics in the two countries would like to bridge their differences instead of widening the gap. And Kishi hopes North China Railway Archive can create one such opportunity.