Fukuryu Special Attack Unit Training Base

The Fukuryu (伏龍, "Crouching Dragon") special attack unit was one of the most desperate suicide weapons developed by the Imperial Japanese Navy in the final months of World War II. Its origins are not clearly documented — some accounts credit Captain Kiichi Shintani of the Yokosuka Anti-Submarine School, while Japanese accounts trace the diving gear to mine-clearance equipment developed at the Navy Engineering School in Yokosuka in early 1945 — but the program aimed to create an underwater defense force against the anticipated Allied amphibious invasion of the Japanese home islands (Operation Downfall).

Fukuryu operators were equipped with rudimentary diving gear consisting of a rubberized canvas diving jacket and trousers, diving shoes, and a steel diving helmet secured by four bolts. Each diver carried 9 kg of lead weights for ballast and breathed from two 3.5-liter bottles of compressed oxygen at 150 bar, with carbon dioxide removed by a sodium hydroxide scrubber canister. The system theoretically allowed a diver to walk along the ocean floor at depths of 5 to 7 meters for roughly five hours (some sources give longer figures). Their weapon was the Type 5 attack mine — a 15 kg explosive charge fitted to the end of a 5-meter bamboo pole. In combat, a diver would thrust the mine into the hull of an approaching enemy landing craft, destroying both the target and himself.

The main training base was established at Yokosuka, where the unit fell under the Yokosuka Anti-Submarine School. Training was conducted at Nobi Beach (野比海岸) in Yokosuka, where the 71st Arashi unit had its headquarters, with the diving gear developed at the Navy Engineering School in Yokosuka. The name Fukuryu appears in the "Navy Assault Unit Organization Ordinance" issued on March 1, 1945, and training began at the Anti-Submarine School in June. Three main units were formed: the 71st Arashi unit based at Yokosuka, the 81st Arashi unit at Kure, and the Kawatana unit at Sasebo.

Training was extremely hazardous. The crude rebreather systems, manufactured under Japan's severely deteriorating wartime industrial conditions, suffered frequent malfunctions. The complex breathing methods required careful management of oxygen flow and carbon dioxide scrubbing, and equipment failures led to drowning, oxygen toxicity, and decompression sickness. At least ten trainees died during training at Yokosuka alone. The diving suits were primitive and the overall concept was recognized even by its planners as a near-certain death sentence.

The original plan called for 6,000 trained Fukuryu operators, but the program was far from complete at Japan's surrender on August 15, 1945: figures for the number of men trained range from about 1,200 to nearly 3,000 depending on the source, and only a few hundred diving suits had been delivered. The Fukuryu were never deployed in actual combat. Today, Nobi Beach is a public beach; air-raid shelters and pillboxes thought to be connected with the unit survive nearby, and a miniature figure of a Fukuryu diver is displayed at the Yūshūkan museum at Yasukuni Shrine in Tokyo, preserving the memory of one of the war's most extreme special attack programs.