The Matsushiro Imperial Underground Headquarters are the ruins of World War II-era military facilities that were scattered around the Zenkoji-daira, mainly constructed under three mountains in what is now Matsushiro, Nagano City, beginning in late 1944. According to the testimonies of former military officials and historical record, the military wished to deal a ‘final blow’ to the Allied Powers during the battle to take the main Japanese island to obtain a more advantageous agreement. These tunnels were intended to be used as a safe base of operations for this planned offensive.

Currently, 500m of the facility under Mt. Zo is open to the public.

Next to the facility is the Matsushiro Memorial Center of Untold History, which documents the construction and legacy of the tunnels.

Mt. Zo Underground Shelter (‘I ’ Area)

This is the largest shelter of the three with a total length of about 6km. By the time Japan surrendered, it was about 80% completed and contained some furnishings, all of which have been removed. There remain many holes where dynamite was set and traces of railroad ties.

Mt. Maizuru Underground Shelter, the Imperial Palace (‘Ro’ Area)

These were intended to function as the Imperial Headquarters for the royal family. While not open to the public, there is still a Japanese-style room there, which was intended to be the Imperial chambers.

Mt. Minakami Underground Shelter (‘Ha’ Area)

This was supposed to be a food warehouse, but there were also some rooms that appear to be for other purposes, such as a Japanese-style room made of cypress and a Western-style conference room. As the tunnels are currently collapsed and in disrepair, visitors are not allowed inside.

Korean Workers

Those who had to do the excavation work were mainly Koreans, forcibly brought from Korea or transferred from various construction sites around Japan. While a few workers were Japanese, it was the Korean workers who were forced to take on the most dangerous and difficult tasks. They laid blasting charges day and night in 2-3 shifts. The total number of the forced workers is estimated to be at least 6,000-7,000 people, but the exact number is unknown, because no records have survived.

A ‘Comfort House’

A so-called ‘comfort house’ (official brothel) was set up in a building in Nishijo Village for those overseeing the construction, and some young Korean women were brought in to work there. While all of these women returned to Korea immediately following the War and we don’t have direct testimonies from them, others have said that the women were told they would be working as ‘special nurses.’

Memorial Museum of Untold History

There have been many efforts by locals to remember the victims of the construction and convey historical fact among Nagano citizens. Volunteer organizations have grown the movement to call for the full-scale preservation and accessibility of the Mt. Zo Underground Shelter and have conducted research into its history since 1986. When the original “comfort house” building was removed in 1991, the Matsumoto Memorial Museum committee was formed with the goal of preserving the materials and eventually building a museum on the site. In February 1998, the Matsushiro Memorial Center of Untold History opened its temporary exhibition room nearby, and in 2013 some materials from the comfort house were used to create an extension to talk about ‘untold history.’

Visitors to the museum can see various items used for the construction, read testimonies (currently Japanese only) from those involved, and speak with members of the organizations involved with preserving the history of this important place.


Matsushiro Imperial Underground Headquarters

Opening Dates: Year-round except New Years (December 29th-January 3rd)
Opening hours: 9 a.m. – 4 p.m. (last entry 3:30 p.m.)
Opening Days: Closed the 3rd Tuesday of each month
Admission Fee: Free

Memorial Museum of Untold History

Opening Dates: March 20, 2021 – November 23, 2021
Opening Hours: 10 a.m. – 4 p.m.
Opening Days: Everyday except Tuesdays
Admission Fee: Adults – 200 yen, Junior High Schoolers – 150 yen, Elementary Schoolers – 100 yen

The easiest route is by car, there is parking available either in front of the Museum of Untold History next to the tunnels, here, or at the city parking about 10 minutes away, here.

It is also accessible using the #30 Alpico bus from Nagano Station (Zenkoji Exit side) for 660 yen. Get off at Matsushiro Hachijuni Ginkou Mae (松代八十二銀行前) and walk about 20 minutes.