On March 19, 1922, Hiroo Onoda is born in Wakayama Prefecture, Japan. Onoda enlisted in the Imperial Japanese Army upon turning 18 years of age, eventually rising to the rank of 2nd Lieutenant before being assigned to the Philippines as an intelligence officer in December 1944. By early 1945, most of the men in his unit had been killed in fighting against the Allies on Lubang Island, leading Onoda to take command of the survivors and take to the hills. With three enlisted men under his command, he began waging a guerilla campaign to harass Allied troops and the local civilian population. In October 1945 (approximately one month after the Japan's official surrender and the end of World War II), the men encountered leaflets announcing the Japanese defeat and instructed the men to surrender; however, Onoda and his men dismissed the leaflets as being propaganda and false. In 1950, one of the enlisted men left the group and surrendered to Philippine forces, though the others continued to fight despite continued leaflets and letters attempting to persuade them that the war was indeed over. In 1954, one of the enlisted men was shot and killed in a fight with a search party sent to find them. In 1972, the last of the enlisted men under Onoda's command was killed in a shootout with police when the two Japanese soldiers had been found burning rice collected by local farmers.

In 1974, a young Japanese explorer by the name of Norio Suzuki came to Lubang and tracked down and befriended Hiroo Onoda; however, Onoda still refused to surrender unless ordered to do so by one of his commanding officers. Suzuki then traveled back to Japan with photographic proof that Onoda was alive and convinced the Japanese government to send Major Yoshimi Taniguchi, Onoda's commanding officer, and ordered him to surrender. On March 9, 1974, Onoda handed over his rifle, ammunition, and other equipment and returned to Japan.

Onoda was welcomed home in Japan, though he himself would grow unhappy with the attention he was receiving as well as the changes in culture and values in Japan, leading him to move to Brazil to raise cattle in 1975. In 1984, he returned to Japan to establish an educational camp for young people, though he would continue to spend a good portion of his time in Brazil. Hiroo Onoda would pass away due to heart failure January 16, 2014, at the age of 91.

2nd Lt. Hiroo Onoda was among the last Japanese soldiers to surrender at the end of World War II. Only one other soldier, Taiwanese-born Private Teruo Nakamura, would hold out longer, who was finally arrested by Indonesian troops on December 18, 1974.