Kuniaki Koiso
A very early discussion on such a tunnel was conducted in 1917 by then-Imperial Japanese Army General Staff officer Kuniaki Koiso. Another early proposal for the project originated in the late 1930s as part of the Greater East Asia Railroad. In 1938, Imperial Japan's Ministry of Communications reportedly decided on a preliminary survey of the sea bottom between Japan and Korea. During World War II the Imperial Japanese government actively pursued the project to connect it with the Korean Peninsula and, ultimately, with the rest of the Asian continent.