Previous late war, the Imperial Japanese Navy decided to set up a fleet headquarters in the bunker in order to escape the air raids. From among a plurality of candidate sites, radio wave condition is good, Hiyoshi which is blessed with access to the Yokosuka is the main naval port has been selected. That had spread Keio University Hiyoshi campus is on the ground, there is a free space in the facility for students has been to one after the troops, also the point it was available as a dormitory of headquarters personnel, became one of the reasons that have been selected .
