In the most fatal recorded mountaineering accident, 199 of the 210 members of an Imperial Japanese Army unit perished in a blizzard on the Hakkōda Mountains.

The Imperial Japanese Army was the principal ground force of the Empire of Japan from 1871 to 1945. It played a central role in Japan’s rapid modernization during the Meiji period, fought in numerous conflicts including the First Sino-Japanese War, the Russo-Japanese War, World War I, the Second Sino-Japanese War, and World War II, and became a dominant force in Japanese politics. Initially formed from domain armies after the Meiji Restoration, it evolved into a powerful modern military influenced by French and German models. The IJA was responsible for several overseas military campaigns, including the invasion of Manchuria, involvement in the Boxer Rebellion, and fighting across the Asia-Pacific during the Pacific War. Notorious for committing widespread war crimes, the army was dissolved after Japan's surrender in 1945, and its functions were succeeded by the Japan Ground Self-Defense Force.

The Hakkōda Mountains disaster occurred on 23 January 1902, when a group of Imperial Japanese Army soldiers became lost in a blizzard in the Hakkōda Mountains in Aomori Prefecture in northern Honshu, Japan, en-route to Tashiro Hot Spring located in the Hakkōda Mountains. The 199 deaths during a single ascent make it the most lethal disaster in the modern history of mountain climbing.

The Hakkōda Mountains are an active volcanic complex in south-central Aomori Prefecture, Japan, in Towada-Hachimantai National Park. Often called Mount Hakkōda or simply Hakkōda (八甲田), the mountains are collectively listed as one of the 100 Famous Japanese Mountains. Its highest peak, Mount Ōdake, lies 21.3 kilometers (13.2 mi) southeast of central Aomori and 28 kilometers (17 mi) west of central Towada and has an elevation of 1,585 meters (5,200 ft). The Hakkōda Mountains are a part of the Ōu Mountains which make up part of the Northeastern Japan Arc, a segment of the Pacific Ring of Fire. The volcanic complex consists of fourteen stratovolcanoes and lava domes arranged into two volcanic groups. The Northern Hakkōda Volcanic Group emerges from the rim of an 8-kilometer-wide (5.0 mi) caldera that dates back to the Pleistocene. The Southern Hakkōda Volcanic Group predates the caldera.