A cache of wartime letters recently released by a Chinese archives has showed that the Japanese soldiers and emigrants felt disillusioned and war-weary during their invasion of China in the Second World War.

The 45,000 letters, among the documents stored at northeast China's Jilin Provincial Archives, were released days ahead of the 77th anniversary of the July 7 Incident which marked the beginning of China's War of Resistance Against Japanese Aggression.

The letters were all written in Japanese during Japan's aggression into China from 1937 to 1945.

One of the letters that was published in the archived Japanese Military Post Weekly in 1938 recorded how a Japanese soldier surnamed Sugimoto was sick of war.

"I simply want to go home! Go Home! I cannot put up with another day here," wrote the soldier who was stationed in China's northeast.

In another letter published in a 1940 Japanese military monthly newspaper, Japanese soldier Chosuke asked his mother to get him back to his homeland by fabricating a lie that she was critically ill.

"I want to go back so much but I cannot make it home," he wrote.

Zhao Yujie, an official with the Jilin archives, said that the letters are "strong proof that the war was not popular even among the soldiers of the nation that launched it."

The letters also recorded how Japanese emigrants became disillusioned after finding out they were cajoled into northeast China, as part of Japan's strategy to control its east Asian neighbor by gradually changing its demographic structure alongside military invasion.

Many Japanese emigrants found that the wealth and prosperity their government had promised them were sheer lies.

"Several days after we arrived at our destination, we know everything [is different from what we had been told]. I feel my dream has been shattered," wrote new Japanese emigrant Gunji in his letter to a friend in Kyoto Prefecture.

Historians have pointed to the irony of right-wing Japanese politicians trying to eradicate the memory of their country's atrocities at a time when more and more evidence of the crimes is emerging.

The release of the letters comes in the wake of the Japanese cabinet passing a resolution this week allowing Japan to exercise the right to collective self-defense by reinterpreting the pacifist Constitution.

The move gave a greenlight to Japan to take military action to defend other countries even if the nation itself is not under attack.

There is fear that this major overhaul of Japan's postwar security policy will further escalate regional tensions in east Asia.

"The newly released letters will hopefully serve as a reminder of Japanese war crimes," said Zhao.