Urban exploration of underground shelters used by forces protecting the island from attack. In a way the large room is a secret lost room as few tourist bring a flashlight with them like I did. This is located on the island of Okunoshima in the Hiroshima Perfecture of Japan at the site of the Tadanoumi poison gas factory. This was built in 1929 and ran until 1945. This mainly produced mustard gas, but made other poisons as well. The island has a museum dedicated to poison gas that is well worth looking at. A great site for urban exploration.
AloJapan.com