During the Meiji Restoration, many “samurai” became officers in the new national army. They and their descendants instilled many samurai beliefs about conduct in the Imperial Japanese Army. Sakae Oba (1914-1992) did not come from a samurai background. His father farmed. The son graduated from a teacher’s academy in 1933, and began working in a school. Soon he married. Within a year, however, he applied to be an officer in the army.
The IJA recruited soldiers into locally-based regiments. Oba became an officer in the 18th Regiment. The 18th had fought in the Sino-Japanese (1894-1895) and the Russo-Japanese (1904-1905) wars. From 1928 on, it did much of its service in China. In 1931, Japan seized the territory of Manchuria; in 1932, Japanese and Chinese troops fought each other around Shanghai.
In July 1937, Japan launched a major invasion of China proper. The 18th Regiment engaged in two months of savage fighting. Oba was promoted to Second Lieutenant in late 1937. The 18th Regiment then fought in the Japanese campaign in central China. Possibly, the 18th Regiment took part in the terrible massacres of Chinese civilians that accompanied these operations. In 1939, he made First Lieutenant. In 1941, he received command of a company. In 1943, he made Captain.
Japan’s war in China bogged down. In late 1941, Japan opted for attacks on the Western possessions in the Far East. The attack on Pearl Harbor, and the conquest of the Philippines, British Malaya and Burma, and the Dutch East Indies (Indonesia) followed. By early 1944, many of the large number of troops in China began to move toward the Pacific islands that blocked the American advance on Japan. In February 1944, an American submarine sank the troop ship carrying the 18th Regiment. Less than half the regiment survived, but Captain Oba was among them. The survivors were taken to the island of Saipan. Rather than being a coral atoll, the island is mountainous and densely forests. The Japanese saw it as part of a last line of defense against the Americans. Oba and his men joined the garrison.
Between 15 June 1944 and 9 July, the Americans conquered Saipan. On 7 July, most of the surviving Japanese soldiers made a “banzai charge,” rather than accept the shame of surrender. When the attack ended, Marines and soldiers counted 4,300 dead Japanese in front of their lines. Almost 30,000 Japanese soldiers died on Saipan, as did about 20,000 civilians.
Captain Oba and 45 of his men were among the survivors. They gathered up several hundred civilians and headed for the woods. Oba’s intentions appear to have been to preserve the lives of his men and to protect the civilians. Occasionally, they staged night-raids on American positions, but these may have been chiefly attempts to acquire food and medicine. Perhaps he had seen enough of massacres and suicides. Despite determined searches by the Marines, Oba held out until 1 December 1945.
Oba returned to Japan, where he found his wife alive. After the war, he worked in a department store.
 Don Jones, Oba: The Last Samurai (1986). Haven’t read it; just read about Oba.
 These include the Nanjing Incident/Nanking Massacre. See: https://en.wikipedia.org/wiki/Nanjing_Massacre Even before the Japanese atrocities of the Second World War, these events had created in the Western mind a reputation for ferocity and bestial behavior on the part of the Japanese military.