Former Hitachi Aircraft Tachikawa Factory Substation

The Former Hitachi Aircraft Tachikawa Factory Transformer Substation is a reinforced concrete building located in Higashiyamato Minami Park, Higashiyamato City, western Tokyo. It is one of the rarest surviving war-damaged industrial structures in the greater Tokyo metropolitan area, bearing vivid physical testimony to the American strategic bombing campaign against Japan's wartime aviation industry.

The building was constructed in 1938 as the transformer substation for the Tokyo Gas and Electric Industrial Company (Tokyo Gasu Denki Kogyo) aircraft engine factory. In 1939, the company merged with Hitachi Manufacturing to form Hitachi Aircraft Company (日立航空機株式会社), and the Tachikawa plant became the company's primary engine manufacturing facility. The substation converted high-voltage electricity from the power grid into the lower voltages required for factory operations. By 1944, the factory had expanded dramatically to employ approximately 13,000 workers — including mobilized students and conscripted laborers — producing aircraft engines at peak wartime production levels.

In the final months of the Pacific War, the factory was targeted in three devastating air raids. On February 17, 1945, U.S. Navy F6F Hellcat carrier-based fighters strafed the facility. On April 19, 1945, U.S. Army Air Force P-51 Mustang fighters attacked the plant. The most destructive raid came on April 24, 1945, when approximately 101 B-29 Superfortress bombers dropped around 1,800 bombs on the factory complex, destroying roughly 80% of the facilities and killing 111 people including factory employees, mobilized students, and nearby residents. The reinforced concrete substation, however, survived all three attacks — though its walls were riddled with machine gun bullet holes and pockmarked by bomb shrapnel.

After the war, the surrounding factory buildings were demolished, but the substation remained operational. It continued to function as an electrical transformer facility until 1993, when it was finally decommissioned. In 1995, Higashiyamato City designated the building as a municipal historic site (市指定史跡) and cultural property, recognizing its irreplaceable value as a physical witness to the air raids. The substation was incorporated into the newly developed Higashiyamato Minami Park (東大和南公園).

Today, the building stands as a solemn memorial in the park, its scarred facade serving as a powerful anti-war statement. The countless bullet holes, shrapnel impacts, and blast damage visible across the exterior walls provide visceral evidence of the intensity of the wartime attacks. The site is sometimes described with the phrase "the Atomic Bomb Dome in the west, the substation in the east" (西の原爆ドーム、東の変電所), drawing a parallel with Hiroshima's Atomic Bomb Dome as a preserved ruin bearing witness to wartime destruction. The substation is open to the public on Wednesdays and Sundays from 10:30 AM to 4:00 PM, and serves as an important site for peace education in the Tokyo area.