Greater East Asia Railroad (大東亜縦貫鉄道 Daitoa Jyukan Tetsudo) was an idea for a railroad linking Japan with the Asian mainland and Europe, formulated in 1938 during the Second Sino-Japanese War leading to World War II. Part of the plan included a tunnel or bridge somewhat similar to the more recent Japan-Korea Undersea Tunnel proposal.
References
Greater East Asia Railroad Wikipedia(Text) CC BY-SA