The three tall structures we could see in the distance from our home-stay were the antenna towers for a longwave radio transmission station completed by the Imperial Japanese Navy in 1922. We drove over to the facility and a docent gave us a pamphlet in English that explained some history of the facility.

Of interest to visitors from the United States is that this facility supposedly transmitted the signal to commence the attack on Pearl Harbor. The message sent from here was said to be "Climb Mount Niitaka 1208".

The towers were constructed with reinforced concrete, some of the earliest and tallest structures using this building method. Each tower is 136 meters tall and the towers form an equilateral triangle, each side is 300 meters.