JULY 8, 2026 – Members assigned to the 374th Civil Engineer Squadron at Yokota Air Base, Japan, transferred World War II-era Imperial Japanese Army aircraft artifacts to representatives of the Japanese government July 1, marking the return of historically significant materials discovered during a construction project on base.
In January, construction crews uncovered the artifacts approximately 7-10 feet below ground during a construction project on base. Initially believed to be unidentified metal debris, the materials were referred for further evaluation after environmental personnel recognized their potential historical significance.
“When these materials were uncovered, I determined they should be assessed for historical significance,” said Callie Oldfield, 374th Civil Engineer Squadron environmental scientist. “We were only able to recognize the true significance of these artifacts because of the knowledge and expertise of the historians and museum curators.”
Oldfield coordinated the initial assessment with the Fussa City Board of Education before assembling a multidisciplinary team led by the Gifu-Kakamigahara Air and Space Museum. The team included aviation historians, museum curators, cultural property specialists and aviation technology experts who conducted an on-site examination of the collection in May.
Researchers assessed the recovered materials were Imperial Japanese Army aviation artifacts consisting of aircraft radiators, engine components, landing gear assemblies, airframe sections and deactivated munitions. Their investigation concluded the collection represents components from multiple Imperial Japanese Army aircraft, reflecting the historical role of Yokota Air Base, formerly Tama Army Airfield, where numerous aircraft underwent testing during World War II.
The team also identified several rare components, including a water cooler from a Kawasaki Ki-61 Hien fighter aircraft, oil coolers from a Kawasaki Ki-45 twin-engine fighter aircraft and an oil cooler believed to be from a Kawasaki Ki-102 fighter aircraft. According to the researchers, some components may be among the few surviving examples of their kind and retain original wartime paint valuable for aviation conservation research.
Following the assessment, Oldfield coordinated the transfer of the artifacts to the appropriate Japanese authorities for continued research, preservation and potential public display. The artifacts were temporarily stored on base while the appropriate Japanese agencies coordinated their acceptance.
“I don’t want to lose a piece of history,” Oldfield said. “Although preserving and assessing artifacts takes time, the best outcome is seeing them used for education and research. I’m excited to see what new information these artifacts will reveal in the future.”
Japanese government representatives visited the base to receive the collection, while members of the engineer squadron assisted with loading the artifacts for transport.
The transfer reflects the continued cooperation between the base and its Japanese partners to preserve historically significant materials discovered during ongoing installation construction and modernization projects.
By Yasuo Osakabe
374th Airlift Wing