The remains of massive underground tunnels secretly excavated in the mountains of Matsushiro in 1944-1945 to prepare for a final homeland battle. Located in Matsushiro, Nagano City, the tunnels extend a total of 75 kilometers through three mountains — Zosan, Maizuruyama, and Minakami-yama — in anticipation of relocating the Imperial General Headquarters, government agencies, and the Emperor. Korea…

The Matsushiro Underground Imperial Headquarters was a secret tunnel complex excavated continuously from November 1944 (Showa 19) until Japan's surrender in August 1945. Under the 'Matsushiro Daihonei Plan' in anticipation of an American landing on the Japanese mainland, approximately 75 kilometers …