Work on this project started in 1992 and represents the underground infrastructure to prevent flooding in the city of Tokyo and its suburbs during the season of typhoons and the rainy season.
This system has five reservoirs with a diameter of 32 meters and a height of 65 meters. Between themselves, they are connected through a tunnel at 6.4 miles at a depth of 50 meters under the ground.
When all the tanks overflow water enters the room height 25.4 meters long, 177 meters and a width of 78 meters. In this hall there are 59 columns of 10 megawatt pumps, which together are able to pump out 200 tons of water every second into the local river Edogawa.