Matsushiro Zozan Underground Imperial Headquarters

Beneath the mountains of Matsushiro lies one of the most sobering historical sites in Nagano: the Zozan Underground Imperial Headquarters, a sprawling network of tunnels excavated in secret during the final year of World War II. As American forces closed in and the bombing of Japanese cities intensified, the military high command drew up plans to relocate the very center of the state — the Imperial General Headquarters, key government ministries, the national broadcaster, and even the Emperor himself — from vulnerable Tokyo to a hidden fortress deep inland. Matsushiro, ringed by mountains and far from the coast, was chosen for this last redoubt.

Beginning in late 1944, tunnels were bored into three mountains — Zozan, Maizuru, and Minakami — in a frantic, round-the-clock effort. The scale was enormous: many kilometers of galleries were blasted through solid rock in a matter of months. The work was carried out under brutal conditions, largely by conscripted Korean laborers alongside Japanese workers, and the human cost was severe. Today the site is preserved not only as a relic of wartime engineering but as a memorial that openly acknowledges the forced labor and suffering involved, with panels documenting the workers' ordeal.

A section of the Zozan tunnels is open to the public, free of charge. Visitors don a provided helmet and walk into the raw, unfinished rock passages, lit just enough to reveal the drill marks, the grid of intersecting tunnels, and the sheer ambition of the plan. The air is cool and still, and the experience is quiet and reflective rather than dramatic — there are no reconstructions or effects, only the bare stone and the weight of what it represents. Interpretive signs explain how the complex would have functioned had the war continued and the mainland invasion the Japanese leadership feared come to pass.

The project was never completed. Japan surrendered in August 1945, and the Emperor and government never moved here. What remains is a vast, unfinished monument to the desperation of a regime preparing to sacrifice everything, and to the laborers who paid for it. In recent decades local citizens' groups have worked to preserve the tunnels and to ensure that the full story — including the exploitation of Korean workers — is told honestly, making the site an important place of peace education.

The tunnels sit within easy reach of Matsushiro's samurai castle town, and the contrast between the two is stark: Edo-period romance above ground, 20th-century tragedy below. Reach Matsushiro by bus from Nagano Station in about 30 to 40 minutes, and set aside an hour for the tunnels. Wear sturdy shoes and bring a jacket, as the interior stays cold even in summer. For travelers interested in the human realities of the war, Zozan is one of the most affecting and least sensationalized sites in Japan.