The Seikan Tunnel, the world's longest undersea tunnel, connects the Japanese islands of Honshu and Hokkaido. Making it took 24 years, and the enormously challenging work claimed many lives. This time on Japanology Plus, we'll dig deep into the dedicated effort and technological know-how that helped to create the Seikan Tunnel. Our expert guest is Toshio Kadoya, who worked on construction of the tunnel for 18 years. And in Plus One, we look at a ferry service that predated the Seikan Tunnel.