Nakajima Aircraft Ota Plant

The Nakajima Aircraft Company Ota Plant (中島飛行機太田製作所) was the nerve center of Japan's largest wartime aircraft manufacturer and one of the most strategically important industrial facilities in the Pacific War. Its story spans from a humble silkworm shed to an aviation empire, wartime devastation, and corporate rebirth.

Origins: From Naval Officer to Aviation Pioneer

Chikuhei Nakajima (1884-1949), a former Imperial Japanese Navy engineering lieutenant, resigned his commission in 1917 to pursue his vision of building aircraft in Japan. In May 1917, he established the Airplane Research Laboratory (飛行機研究所) in a converted silkworm-rearing shed in Ojima-machi, Nitta District, Gunma Prefecture (now part of Ota City) — his hometown. The initial workforce numbered just nine people, including Nakajima himself and a cook.

By December 1917, Nakajima formally retired from the Navy and relocated the workshop to Ota-machi. The enterprise grew rapidly through military contracts, evolving through several name changes: Nihon Hikoki Seisakusho (Japan Aircraft Manufacturing Works), Nakajima Hikoki Seisakusho, and finally Nakajima Hikoki Kabushiki Kaisha (Nakajima Aircraft Company, Ltd.) on December 15, 1931.

The Ota Main Plant

In 1934, a massive new airframe assembly factory was completed in central Ota, covering approximately 150,000 square meters (45,000 tsubo). Emperor Showa visited the new Ota Plant on November 16, 1934, underscoring its national importance. On April 20, 1940, the Ota Plant was designated exclusively for Imperial Japanese Army aircraft assembly, while naval aircraft production was concentrated at other Nakajima facilities.

The Ota complex included the main assembly plant, engine testing facilities, an adjacent airfield for flight testing, and extensive worker housing. A dedicated railway spur connected the factory to the national rail network for materials and finished aircraft transport.

Wartime Production: The Arsenal of the Army Air Force

At the outbreak of the Pacific War, the Ota Plant had active production lines for several critical Army aircraft types:

• Ki-43 Hayabusa (隼, "Peregrine Falcon"): The Army's primary fighter from 1941-1943, which saw action across every theater of the Pacific War. Total production across all plants reached 5,919 units.
• Ki-44 Shoki (鍾馗, "Demon Queller"): A high-speed interceptor designed for home defense against heavy bombers, with approximately 1,225 built.
• Ki-49 Donryu (呑龍, "Dragon Swallower"): A twin-engine heavy bomber used extensively in China and the Southwest Pacific, with 819 produced.

From 1944 onward, production increasingly shifted to what would become the plant's most significant product:

• Ki-84 Hayate (疾風, "Gale"): Widely regarded as the finest Japanese Army fighter of the war. Powered by the 2,000-horsepower Nakajima Ha-45 (Homare) engine, the Hayate combined speed (maximum 624 km/h), heavy armament (two 20mm cannon and two 12.7mm machine guns), pilot armor protection, and self-sealing fuel tanks. First flown in March 1943, it entered mass production in 1944. By December 1944, monthly output reached 373 units — the highest single-month production figure for any Japanese Army fighter. Over the course of the war, approximately 3,514 Ki-84s were built, with the Ota Plant serving as the primary production center. The type saw combat in the Philippines, Burma, China, Manchuria, and over the Japanese home islands, earning Allied respect under the reporting name "Frank."

Strategic Bombing: Seven Raids on Ota

American strategic planners identified the Nakajima Ota Plant as a priority target due to its critical role in fighter production. Beginning in late 1944, the US XXI Bomber Command launched a sustained bombing campaign against the facility:

1. Late 1944 (initial raids): Early high-altitude precision bombing attempts with limited effectiveness.

2. February 10, 1945: The most devastating single raid. Approximately 120 B-29 Superfortresses of the 73rd and 313th Bombardment Wings were dispatched, with 84 aircraft successfully bombing the primary target. Over roughly 40 minutes of wave attacks, the eastern half of the Ota Plant was destroyed. The raid killed 152 people in Ota town alone, injured 187, and completely destroyed 213 buildings. On the assembly lines, 74 Ki-84 fighters were destroyed or damaged, temporarily halting production.

3. Subsequent raids through August 1945: The factory was bombed a total of seven times before the war's end, progressively reducing its production capacity.

In response to the bombing campaign, Nakajima undertook an emergency dispersal program beginning in January 1945. Manufacturing was relocated to semi-underground and underground facilities, including sites at Shiroyama and Oya (the latter utilizing volcanic tuff caves in Tochigi Prefecture). However, dispersal drastically reduced efficiency due to corrosion from underground humidity, poor ventilation, transportation bottlenecks between scattered sites, and chronic worker absenteeism as morale collapsed under sustained bombardment. By war's end, the Shiroyama underground facility had completed only four wing and fuselage assemblies.

A remarkable 1-minute-30-second film recording of the February 10, 1945 air raid — shot clandestinely despite strict wartime prohibitions on photographing air raids — was rediscovered in 2024 after being lost for 40 years, providing rare visual documentation of the destruction.

Dissolution and Rebirth

Following Japan's surrender in August 1945, the Supreme Commander for the Allied Powers (SCAP) prohibited all aircraft production and research. Nakajima Aircraft Company was renamed Fuji Sangyo (Fuji Industries) in 1945, but unlike Mitsubishi Heavy Industries which had diversified into shipbuilding and general machinery, Nakajima's overwhelming dependence on military aviation left it vulnerable. In 1950, the company was forcibly dissolved into 12 separate successor companies under the Zaibatsu dissolution program.

In 1953, five of these successor companies reunited to form Fuji Heavy Industries, Ltd. (富士重工業株式会社). The new company initially produced the Fuji Rabbit motor scooter before launching the Subaru automobile brand in 1958. The Ota Main Plant was repurposed for automotive manufacturing, producing Subaru's iconic lineup. In 2017, Fuji Heavy Industries officially changed its corporate name to Subaru Corporation (株式会社SUBARU), completing a century-long transformation from silk country aviation workshop to global automobile manufacturer.

Today, the SUBARU Gunma Manufacturing Division Main Plant (群馬製作所本工場) stands on the exact site of the former Nakajima Aircraft Ota Plant. The factory address — Subaru-cho (スバル町) 1-1, Ota City — reflects the deep connection between the company and its birthplace, with the surrounding neighborhood officially named "Subaru Town" by the municipal government. The town of Ota embraces its aviation heritage, with the Nakajima Chikuhei Memorial Museum and various monuments throughout the city commemorating the era when this quiet Gunma town was the heart of Japan's military aviation industry.