YOKOHAMA, Japan — Hidden beneath the greenery and school buildings of Keio University's Hiyoshi campus in Yokohama is the former command center of the Imperial Japanese Navy's Combined Fleet.
The fleet's command center was originally found on flagships - like the battleships Mikasa and Yamato - from which an admiral could direct naval operations. But as World War II progressed, Japan's military power started to wane. With only a few lead ships left, the navy had no choice but to transfer the command center to land.
Keio University's Hiyoshi campus was selected due to its location on a hill, a distinct feature that allowed for optimum radio reception. In September 1944, the command center was transferred to a dormitory on the west side of campus, and a 2,600-meter-long tunnel was dug under the nearby hill. From the confines of this underground bunker, which offered shelter from U.S. bombings, navy officers resumed their strategic planning and decision making.
The university organized a public tour of the Hiyoshi tunnels on June 23. The entrance to the historic site can be found next to a volleyball court on the southeast side of campus.
Inside the tunnel, the air is cold. You need the help of a flashlight to walk down an incline until you reach your destination 30 meters underground. At the end of the journey, you discover a concrete bunker containing many rooms connected by a network of three-meter-wide corridors. Each was given a different moniker, such as the "Admiral's Office," the "Operations Room" and the "Code Room."
One of those compartments was known as the "Radio Room." It was used to receive encoded status messages from naval ships in battle.
"We learned that Japan was losing the war, for example with the Battle of Okinawa. It was devastating for us," said 84-year-old Ichiro Hirata of Tokyo. A former naval officer in charge of decryption, Hirata was assigned to the naval command at the age of 14 in June 1945, just before the war's end. Back then, the tunnel was brightly lit with fluorescent lights, and the team deciphered code around the clock in four shifts, he said.
On Aug. 6, 1945, they received an encoded message from the Imperial Headquarters that read: "New bomb dropped on Hiroshima. Grave damage." As they continued deciphering, they found out that a second atomic bomb had hit Nagasaki. Talking about the contents was prohibited, but the decoders whispered to one another, "Japan might be done for."
On Aug. 15, everybody except those on duty were summoned at noon and told to line up in front of a radio outside the tunnel. The cicadas were chirping so loudly they could hardly hear the Emperor's voice as he read the Imperial Rescript on the Termination of the War. One of their superiors later informed them that Japan had been defeated.
They spent roughly the next two weeks burning telegrams and decryption manuals. "I felt the long hours that I had sacrificed at night, memorizing codes instead of sleeping, likewise burning away to nothing," Hirata said.
Access to the Hiyoshi tunnels is normally restricted. However, the Association to Preserve the Hiyoshidai Tunnels, a local civic group, has received permission from the university to conduct public tours once a month.
The association's chairman is Takeshi Akuzawa, 51, a teacher at Keio Senior High School. He said the command center used to receive messages from kamikaze pilots. When kamikaze planes approached enemy ships, their pilots would continuously transmit "dah" in Morse code. When that sound went dead, it meant that the pilots were gone, too.
One of the entrances to the tunnels was destroyed two years ago to develop residential land.
"Orders for suicide missions were issued here," Akuzawa said. "The underground bunker has to be preserved to teach younger generations about the reality of war."
Keio University's Hiyoshi campus was built in 1934. It covers about 430,000 square meters, or nine times the area of Tokyo Dome. A concert hall and a gym can be found on campus today, as well as historically important buildings and artworks.
Building No. 1 is currently used by Keio Senior High School. On one of its walls is a relief showing the date of its construction according to the Gregorian and Japanese Imperial calendars, "1934/2594."
Below the relief is a cup on which a world map is engraved. The regions occupied by Japan were reportedly colored in red during World War II.
A chapel endowed by graduates of the class of 1937 still remains today. During the war, the navy used it as a place to monitor foreign radio broadcasts. The mushroom-shaped concrete structure near the chapel acts as a cover for the entrance to the underground bunker.
More than 3,000 students from Keio University were mobilized and sent to the battlefield, and nearly 400 were killed. Economics student Ryoji Uehara died at the age of 22 as a kamikaze pilot. The night before his suicide mission, he jotted down his thoughts as a will.
"I am merely an atom of iron in a magnet that clings to an enemy aircraft carrier, possessing neither personality, emotions or reason," he wrote. "Tomorrow, another liberalist will depart from this earth."
The campus was requisitioned by the U.S. military in September 1945. When Keio's Mita campus in Tokyo was also destroyed in air raids, the university reportedly had trouble securing enough classrooms for its students. The Hiyoshi campus was returned to Keio in October 1949.