Asakawa Underground Aircraft Engine Factory

The Asakawa tunnels were excavated beneath the hills near Takao in Hachioji between September 1944 and August 1945. They were intended for army stores and the dispersal of Nakajima's Musashino aircraft-engine works as air raids threatened production. The complex comprises the I, Ro and Ha districts. The I district became a factory, while other sections remained unfinished, preserving evidence of the hurried industrial projects of the final war years.

Drilling and blasting marks and impressions left by transport-track sleepers survive inside. An account published by Hachioji's civic activity support centre also discusses Korean workers forced to take part in excavation. The site therefore documents both aircraft production and the wartime labour behind underground construction.

Preservation work grew from investigations by a teacher and students; the preservation group was established in 1997 and continues research, guided visits and peace education. Tours cover only part of the I district. The approximate map point follows the I-district marker embedded in the group's event page, rather than defining the extent of the underground complex.

Visits require advance registration under the group's current announcements. Meeting points and routes depend on the individual tour. The dark, damp tunnels have exposed rock surfaces, and visitors need helmets, lighting and suitable walking equipment. A mapped entrance does not imply permission for independent entry; access remains subject to on-site safety conditions.