Nearly 90 newly sorted documents of the Japanese military during its occupation of Northeast China from 1931 to 1945, just released by Jilin Provincial Archive in Changchun, once again revealed Japanese war atrocities and proved how wrong Japanese right-wing politicians have been.

Changchun once served as the headquarters of the Japanese Kanto Military Police and "capital" of Manchukuo, a puppet state created by Japan then. The archive keeps more than 100,000 historical documents, about 90 percent of them written in Japanese, the world's largest open record on the issue and irrefutable proof of Japanese invasion and occupation of and atrocities in China.

The Japanese army set fire to many of its war documents and buried the remaining ones before it made a slapdash withdrawal from China after Japan surrendered to the Allied forces on Aug 15, 1945. The buried documents were found when workers began digging a construction site in the 1950s.

These original documents provide ample historical evidence of the crimes the Japanese army committed before and during World War II. These documents prove yet again that the Japanese did commit heinous crimes like the Nanjing Massacre and the practice of "comfort women" irrespective of the denials of the present Japanese government.

One of the newly sorted documents shows that Nanjing's population declined sharply from 1.13 million to 345,000 in two and a half months, that is, before and after the 1937 Nanjing Massacre. A report in a Japanese newspaper says "floating dead bodies covered up to 3 miles ... in the Yangtze River", further demonstrating that not only did the Japanese carry out the massacre, but also that the number of victims was higher than the previous estimates of 300,000.

A document issued by the Japanese authorities identifies another heinous crime - wartime "comfort women", or women forced into sex slavery by Japanese authorities - as an official act sponsored by the Japanese war regime. One file in the archive specifically records that a "comfort woman" in Nanjing was "exploited" (raped) by at least 71 Japanese soldiers in 10 days.

But despite the sea of evidence against the Imperial Japanese Army, Japanese right-wing leaders keep denying Japan's wartime crimes. In 2012 Toru Hashimoto, mayor of Osaka, said that sex slaves played a "necessary" role in keeping Japanese troops in check during World War II. A month ago, Japan's Chief Cabinet Secretary Yoshihide Suga denied Chinese President Xi Jinping's statements on Japanese invasion of China and the Nanjing Massacre. Worse, on April 21, Japanese Prime Minister Shinzo Abe sent a ritual offering to Yasukuni Shrine, which honors 14 Class-A war criminals and is a symbol of Japan's militarist past. Abe even visited the shrine four months ago.