From When the Shooting Stopped: August 1945, by Barrett Tillman (Osprey, 2022), Kindle pp. 180-182, 187:
VJ Day also was Survival Day to large numbers of prisoners of war and internees in Japanese hands. In August approximately 150,000 Allied personnel were thought held captive in some 130 camps throughout Asia. However, a complete accounting revealed 775 facilities in the Japanese Empire; 185 in Japan itself.
The prisoners represented not only the U.S. but Britain, Australia, New Zealand, Canada, the Netherlands, and India. Approximately 36,000 soldiers and sailors were sent to Japan itself with most of the balance in the Philippines, China, Korea, Burma, Malaya, Java, and various Pacific islands. Japan also held large numbers of civilian prisoners and internees, as many as 125,000, mainly in the Dutch East Indies and Philippines, with more than 10 percent in China and Hong Kong. That figure excluded Nationalist Chinese personnel. Frequently the Imperial Army killed Chinese prisoners as a matter of policy.
One quarter to one third of Anglo-American prisoners held by Japan had died in captivity, with about 12 percent dying in the Home Islands. In contrast, about 3 percent of Western POWs perished in German Stalags. War crimes investigators later determined that 27 percent of Allied POWs in the Pacific died in captivity – officially seven times the rate of Western POWs in German camps.
Allied POWs existed in a hellish world of perennial malnutrition during Japan’s food shortage amid disease and routine brutality. Postwar investigators often referred to ritual or informal executions but the killings were largely extrajudicial or, to put it bluntly – murder.
Though Tokyo had signed the Second Geneva Convention in 1929, the government had never ratified the agreement regarding treatment of prisoners of war. After a qualified pledge to abide by the convention in early 1942, Japan quickly reverted.
Prisoners endured horrific conditions in captivity, eventually subsisting on 600 calories per day. What few Red Cross parcels arrived often were confiscated by the captors. The situation could hardly have been improved in the final months of the war, however, because in mid-1945 virtually all Japanese civilians were also malnourished.
Almost lost amid war’s end was the residue of its origin: Japan’s conquest of the Dutch East Indies’ petro-wealth. In 1940 Tokyo had requested half of the Dutch oil exports, but officials in the capital Batavia replied that existing commitments permitted little increase for Japan. That response set the Pacific afire. With only two years’ oil reserves on hand, and denied imports from the U.S. and Java, Tokyo’s warlords launched themselves on an irrevocable course.
The Japanese had to sort out a large, diverse population of some 70.5 million. Upwards of 250,000 were Dutch, mostly blijers, Dutch citizens born in the East Indies. Around 1.3 million Chinese had enjoyed preferred relations with the Netherlands’ hierarchy, but there was also a small Japanese population.
Conquest of the archipelago only took 90 days, ending in March 1942. Japan pledged Indonesian independence in 1943 but never honored it. And despite the Asia for Asians theme of the Greater East Asia Co-Prosperity Sphere, Indonesians suffered terribly under Japanese rule. The new rulers interned all Dutch military personnel and 170,000 civilians. Conditions were appalling: approximately 25,000 died in captivity. Estimates range between 2.5 and 4 million total deaths, more than half of whom perished during the Java famine of 1944–45.
Additionally, millions of Javanese were pressed into servitude elsewhere, notably on the Burmese railroad.