Shimofusa Air Base (Shimohusa Air Base, 下総航空基地, Fujigaya Airfield, Shiroi Air Base)

Shimofusa Air Base is a Japan Maritime Self-Defense Force (JMSDF) aerodrome located in Kashiwa, Chiba Prefecture, straddling the border with Kamagaya. Established in April 1945 as Fujigaya Airfield for the Imperial Japanese Army Air Service, the facility was constructed on the grounds of a former golf course. During the final months of World War II, it hosted the 116th Airfield Battalion and the 53rd Air Combat Group, which operated Ki-45 Kai aircraft for the air defense of the Kanto Plain.

Following the surrender of Japan, the United States Eighth Army occupied the site in September 1945. Redesignated Shiroi Air Base under the Fifth Air Force, the installation functioned as an auxiliary airfield and alternate Air Defense Control Center. The United States Air Force operated various units at the site, including troop carrier wings and security wings, until 1959. Following a joint-use agreement, the base was returned to the Japanese government in June 1960 and redesignated as JMSDF Shimohusa Air Base.

The base currently serves as the headquarters for the JMSDF Air Training Command and the Shimohusa Air Training Group. It hosts the 3rd Service School, the 203rd Air Training Squadron, and the 203rd Maintenance and Supply Squadron. A detachment of the JMSDF Communications Command, specifically a Mobile Communications Squadron, and a detachment of the Criminal Investigation Command are also stationed at the facility. While the base served as the headquarters for the Fleet Air Force and Fleet Air Wing 4 during the 1960s, these units relocated to Naval Air Station Atsugi in 1973, shifting the installation's primary mission to personnel training.

Operational infrastructure supports the use of Kawasaki-Lockheed P-3C Orion maritime patrol aircraft and NAMC YS-11 training aircraft. Previous facility residents included the Shimohusa Rescue Squadron, which operated UH-60J and S-62J helicopters until 2008, and the 205th Air Training Squadron, which operated YS-11T aircraft until 2011. In addition to training facilities, the base maintains specialized maintenance and supply infrastructure to support its maritime patrol and training fleets.