Private Tamura, a writer, is ridden with tuberculosis and is sent away from his unit to a military hospital, only to be refused admission because the ward is already full. He is shuffled back and forth between treatment and orders, until officials essentially tell him not to return and urge him to end his own life rather than try again.
Alone, Tamura discovers that military discipline has collapsed as the Japanese army dissolves into the jungle, subsisting largely on yams. He scavenges what he can, stealing food from local Filipinos while the war’s absurd horror unfolds around him: a despondent soldier self-destructs with a grenade, and others lie dying from malnutrition or injuries along the road. In the chaos, he encounters two soldiers, Yasuda and Nagamatsu, who try to trade cigarettes for yams with passing troops. He declines the cigarette but offers Nagamatsu a yam out of pity, a small act of compassion in a sinking world.
The struggle for survival continues as Tamura forages and the air above the path is punctured by American aircraft strafing the scattered units. At what seems to be an abandoned church, he stabs a dog, a grim sign of the moral fray closing in on him. He soon comes upon a pile of Japanese corpses and, beneath a floorboard, discovers a cache of salt, but his discovery is betrayed when two Filipino civilians uncover him. In a panicked haze, he shoots one of them; the other escapes, and Tamura’s shots miss their mark.
Tamura escapes with his stolen food, abandoning his rifle in the process. He then joins up with remnants from another company and learns that the army’s orders are to retreat to Palompon. He travels with them, trading his salt for yams, while morbid jokes circulate about cannibalism in the New Guinea campaign—a chilling possibility Tamura can’t quite decide if it’s a joke or a grim truth.
Crossing an open road at night becomes deadly as American and Filipino forces gun down Japanese soldiers trying to retreat. In a desperate moment, Tamura prepares a white flag to surrender to a passing American jeep. Just before stepping out, he watches another Japanese soldier do the same; that soldier is shot by a vengeful Filipino woman in the jeep, despite the American soldier’s attempt to take the surrender. Tamura realizes that crossing the road to Palompon is futile and turns back into the jungle.
Delirious and hearing corpses speak in his fatigue, Tamura is found and saved from starvation by Nagamatsu, the man he had given a yam to earlier. He is fed bark, water, and “monkey meat,” while being bullied into giving his grenade to Yasuda, whose leg is wounded and rolled up for protection. After hearing a shot, Tamura races after Nagamatsu and discovers that Nagamatsu had fired on a fleeing Filipino civilian; the so‑called “monkeys” he hunted were other humans all along. The uneasy alliance between Nagamatsu and Yasuda fractures as both fear the other will kill for meat.
With the only source of clean water guarded, Yasuda is forced out, and the two men clash as Nagamatsu shoots Yasuda when he tries to negotiate. In the ensuing struggle, Tamura seizes the rifle and shoots Nagamatsu, who coldly tells him—before dying—that he knew Tamura would eat him.
The scene shifts to post-war Japan, where Tamura writes a memoir of these events. He claims to awaken in an American field hospital in his notes and to have little memory of what happened after shooting Nagamatsu, yet the memory lingers and hovers over him as he dry heaves at the recollection.
