I thought this would be a good terrain reference for late Pacific War fighting, particularly on Okinawa and speculative invasion of Japan scenarios. These concrete single-aircraft shelters would be spread out, making it hard to damage multiple shelters at once. These shared examples are from Chofu (Tokyo), Usa (Oita), Saiki (Oita), and Yomitan (Okinawa). You’ll notice variations in the individual designs.
According to Yomitan, Okinawa, signage, the local shelters were made by stacking drums and covering them with soil to create the dome, cement bags were laid over it and then concrete was poured on. The drums and soil were removed after the concrete cured. I do not know if this particular method was used at the other shelter sites.
Construction on Chofu Airport began in 1939 and used prisoners and junior high school students (middle school in US) for labor. It was taken over by the Imperial Japanese Army and used for air defense of Tokyo. Approximately 30 hardened shelters and 30 open cay hangars were constructed in 1944 by Army personnel, construction workers, a local gardening club, and (again) lots of junior high school students. Two hardened shelters remain at Musashino no Mori Park along with the concrete base of an anti-aircraft position. These particular shelters are partially submerged below ground level, so appear lower than they should be.
Bizarre side note: The strangest kamikaze story related to Chofu Airport took place in 1976 when a nationalist adult film actor / amateur pilot took off from here to make a kamikaze attack on a yakuza leader involved in the Lockheed scandal.





Okinawa Kita Airfield in Yomitan Village was constructed by the Imperial Japanese Army in 1943 and hardened shelters were added the following year. This is the only remaining shelter.


Saeki (Saiki) Naval Air Corps opened in 1934 as an Imperial Japanese Navy seaplane base and advanced training base on Saiki Bay. Saiki would also stand-in for Pearl Harbor in the November 1941 training exercise in preparation for the real attack a month later.



Usa Naval Air Corps opened on Oct. 1, 1939 as an advanced training base for Nakajima B5N “Kate” Type 97 torpedo bomber and Aichi D3A “Val” Type 99 dive bomber crews. In February 1945, Usa shifted from training to operations and was used for kamikaze attacks. In retaliation, Usa was hit with 10 air raids leaving it a smoldering ruin but still partially functional. It’s hardened shelters are mostly used by local farmers as tractor barns but one is maintained as a memorial. 193 kamikazes were sent from Usa, 154 did not come back.


