More than 60 years had passed, but Akira Makino still suffered nightmares about Filipino hostages and the injections that rendered them unconscious. Then there was the one about the surgical knife gouging a human liver.
Every time he woke up to the flashbacks of horrific killing scenes, he shut his eyes tight and tried to turn his mind away from something he no longer wanted to think about.
But Makino, 84, also felt he had to speak out about his wartime experiences to as many people as possible during the final years of his life.
"These were nothing but living-body experiments," Makino said as he sat on a bench wearing just his pajamas at a hospital in the western Japanese city of Osaka, making some of his last comments before he died earlier this year.
"My captain combat-surgeon often showed us human intestines, and said this was the liver and that was that and so on," he said. "He did that to train us. The captain said if he died, we would have to take up a scalpel to conduct the operations instead of him."
Makino, a low-ranked medic deployed to a Philippine island during the final years of World War II, began making his striking statements on Japanese war atrocities in public just last year.
He was regarded as the first former Japanese soldier to have been stationed in the Philippines to speak of experimenting on live hostages and his remarks caused some controversy as historical memory remains a point of simmering friction between Japan and the countries it invaded.
Nationalist Internet sites launched a campaign branding Makino a liar.
Makino said what he experienced was not systematic atrocity, but rather a glimpse of soldiers' desperation during the last-ditch struggle of a nation on the verge of defeat.
It was one year before Japan's surrender when Makino landed on the southern Philippine island of Mindanao in August 1944.
He was assigned as a medic in the 33rd coast guard squad of about 20 soldiers who were in charge of detecting enemy airplanes.
His squad joined a landing force of some 1,500 troops on the fabled Yamato, once the world's largest battleship, which US bombers sank later in the war.
"The Yamato was such a huge ship that it could not easily find a suitable port," he said. "So the ship anchored in the middle of Manila Bay and we dispersed to a variety of destinations in the Philippines."
Soon after arriving at the Japanese military base at Zamboanga on the western tip of Mindanao, Makino found himself and his unit cut off from headquarters, with the situation growing worse by the day.
They received no military supplies or orders, let alone medical packages.
The main enemy facing the small Japanese squad were the guerrilla bands formed by local Muslim Moros, who constantly threatened their station, he said.
"We were told the Moros were such cruel people that they attacked enemies with spears and we actually rescued some people assaulted by them," Makino said. "I was told many times I should not walk in the palm tree jungle after dark."
Naturally, he said, almost all the hostages they captured were Moros. "We were supposed to keep them alive in captivity, but it was no problem if we `disposed' of them, in the beheadings the Japanese have become infamous for," Makino said.
He remembered at least 50 hostages being killed, "including those who got this," he said, moving his hand to imitate a sword cutting off a head.