The road once used by the Korean messengers traveling to Edo. The messengers would depart from Seoul, take to a ship from Pusan and then cross the Seto Inland Sea from Tsushima, then take the Yodogawa River to Kyoto before heading overland along the Nakasendo and Tokaido roads. The length of this journey was approximately 2,000km, with the roundtrip taking about a year.