Ōsawa aircraft bunkers, Musashino no Mori Park (掩体壕 大沢1号・2号) 掩体壕 大沢1号・2号

Of about sixty, four remain, and you see these two from behind a fence

An entaigō is a reinforced-concrete shelter, open on one side and with a vaulted roof, built to keep an aircraft safe from bombs. Around Chōfu Airport, which during the war was an army airfield, about sixty were built around 1944: about thirty in concrete and about thirty in horseshoe-shaped rammed earth. They served to scatter the fighters instead of keeping them in a row, so that a single pass of bombers would not catch them all, and to hide their number from anyone photographing from above. The aircraft were pushed in and pulled out by hand. Today four remain: two here, in Musashino no Mori Park in Mitaka, and two in Fuchū. The park keeps them as war ruins, and explains them as shelters built to preserve the fighters for the final battle on home soil, which is the phrase the Japan of 1944 used for the invasion it expected and that never came.

Tokyo

調布飛行場, Tama

https://theanimetrip.com/luoghi/entaigo-osawa-musashino-no-mori