Tokuyama Naval Fuel Depot

The Tokuyama Naval Fuel Depot (徳山海軍燃料廠) traces its origins to the Tokuyama Naval Coal Briquette Manufacturing Facility (海軍煉炭製造所), established in 1905 in Tokuyama, Yamaguchi Prefecture. The town of Tokuyama actively recruited the facility, seeking economic revitalization after the railway extended to Shimonoseki in 1901. The site's proximity to the Omine coalfields and its excellent natural harbor made it an ideal location for naval fuel operations.

In 1921 (Taisho 10), the facility was reorganized from a coal briquette plant into the Tokuyama Naval Fuel Depot, with divisions for mining, coal processing, oil refining, and research. The commandant's position was elevated to rear admiral rank, and a Western-Japanese hybrid residence was constructed in 1926 for the commandant — this building survives today as the Shunan City Mayor's Official Residence and was designated a Registered Tangible Cultural Property in 2008.

With Japan's expansion into Southeast Asia in 1941-1942, the depot was redesignated the Third Naval Fuel Depot (第三海軍燃料廠) and became one of the Navy's principal petroleum refining centers alongside the Second Naval Fuel Depot in Yokkaichi. After the occupation of the Dutch East Indies oil fields, crude oil shipments from the south dramatically increased production. The facility contained 12 massive underground storage tanks, each capable of holding 50,000 tons of crude oil or heavy fuel oil, built by 1942.

As the war turned against Japan from 1944, raw material supply lines were severed by Allied submarine warfare, and production declined steeply. On May 10, 1945, 60 B-29 Superfortresses of the 73rd Bomb Wing struck the Tokuyama Naval Fuel Station, arriving at approximately 11:00 AM at altitudes of 15,000-20,000 feet. The Oura oil tank facility suffered devastating damage. On July 26-27, 1945, additional firebombing raids targeted both the fuel depot and the city of Tokuyama itself, leaving the facility beyond recovery.

Following Japan's surrender on August 15, 1945, the facility was placed under Allied occupation authority and subsequently transferred to the Ministry of Finance. In 1955 the site was returned to civilian control, and in 1956 Idemitsu Kosan acquired the property, completing its first oil refinery in 1957. The underground fuel tanks were buried during park construction in 1968, but oil continues to seep from the remnants beneath what is now the Shunan Green Space (周南緑地), flowing into the nearby Kinugawa River — a haunting reminder of the depot's wartime past.