A diary kept by a member of the Imperial Japanese Navy, recounting fierce battles in Siberia when Japan dispatched troops there in the early 20th century, was recently unearthed by Kyodo News.
There are few detailed accounts of the war by Japanese troops, with historians relying mainly on official war records.
"A plume of black smoke filled the sky and corpses were washed ashore one after another onto the riverbank," according to the diary, which also depicts how the Japanese forces set fire to a village and gunned down locals.