This model shows the shield-diggin machine used for the construction of Kanmon Submarine Tunnel that was opened on November 15th, 1942 as the first submarine tunnel in the world. Mr. Murayama (1911 - 1995), a later professor of Kyoto University, designed the machine shortly after he joined the Railway Ministry upon graduating from the Department of Civil Engineering at Kyoto Imperial University. He designed the machine from scratch, relying solely on experience and knowledge of tunnel construction in Japan. Because it was wartime, it was not possible for Japan to receive technical assistance from abroad. This machine marks the beginning of shield engineering in Japan.