Thirty meters below Keio University's Hiyoshi campus on the outskirts of Yokohama's Kohoku Ward lies a major site of World War II history: the Hiyoshidai Tunnels (Hiyoshidai Chikago), from where the Imperial Japanese Navy commanded some of their final and most destructive battles.

The 5-km-long tunnel complex survived three air raids and has weathered nearly 70 years since the end of the war.

But some now feel that not enough is being done to preserve the site, and fear that the significance of the tunnels and their history are being forgotten. When sections of the tunnels were destroyed in a development project this spring, these worries would appear to have been proven warranted.