Residents of Beppu, Oita Prefecture, have been intrigued by the recent discovery of two mysterious underground tunnels in an area formerly used by Allied Occupation forces.
A 150-meter-long tunnel was found at Beppu Shogyo Senior High School, while a 400-meter underground passage was discovered in the city's Tsurumien district.
Both tunnels are around 1 to 2 meters in height and width.
The entrances were found in May and October by Tokyo-based contemporary artist Kenji Yamada, 29, who started searching for underground passages after learning from an elderly local resident that Allied forces had constructed an extensive network of tunnels.
According to municipal authorities, Allied forces confiscated around 80 hectares of land in Beppu in 1946 to house about 3,000 troops. Lodgings for officers were based in the area where the tunnels were found.
"Tunnels of about 20 km in total were dug for water pipes and to store other equipment at the (Occupation forces') base. The tunnels found may be part of the underground network," said Shoei Sato, 82, who used to work at the base.
Some locals, however, believe they may have been built as emergency evacuation routes around the time of the Korean War, in the early 1950s.
"During the Korean War, it was believed the base could possibly come under aerial bombardment. It would not be surprising if they were dug as contingency evacuation routes," said Kenichi Toyama, 74, of the city's cultural asset protection board.