Former Japanese Navy Underground Headquarters

The Former Japanese Navy Underground Headquarters is a tunnel complex excavated beneath a hill in Tomigusuku City, Okinawa Prefecture. In August 1944, as the decisive Battle of Okinawa loomed, approximately 3,000 members of the Navy's 226th Construction Unit (the Yamane Unit) began digging the complex by hand. Construction was completed in roughly four months, producing a semi-circular network of tunnels 450 meters in total length and 20 meters below ground, reinforced with concrete and pit props.

The complex served as the operational headquarters of the Okinawa Naval Base Force under Rear Admiral Minoru Ota. Approximately 4,000 naval personnel lived and worked inside the tunnels, enduring relentless American naval and air bombardment. As U.S. forces closed in during the final phase of the battle, Ota sent his famous last telegram to the Imperial Navy Ministry on June 6, 1945, pleading for special consideration for the Okinawan civilians who had sacrificed so much. On June 13, 1945, Ota and members of his staff committed suicide inside the bunker rather than surrender.

When the tunnels were unsealed in the 1950s, the remains of over 2,000 Japanese sailors were recovered. Grenade blast marks and shrapnel scars from the mass suicides remain visible on the walls of the commander's room and staff quarters to this day.

In 1970, approximately 300 meters of the tunnel complex were opened to the public as part of the Kaigungou Navy Headquarters Park. The site includes a resource center and memorial tower dedicated to the fallen. Visitors can walk through the commander's room, staff offices, medical rooms, cipher rooms, and communications center, all preserved as wartime relics. The facility serves as one of Okinawa's most important peace education sites, conveying the horrors of the Battle of Okinawa to future generations.