Chayamachi station is a JR West’s station in Kurashiki, Okayama prefecture. The station serves two lines which are nominally called Uno-port line and Seto-Ohashi line.
However, these names are not the official ones. JR West calls Seto-Ohashi line for Okayama-Kojima which Chayamachi is located en route. However, Okayama-Chayamachi is officially Uno line and Chayamachi-Kojima is Honshi-Bisan line. Chayamachi-Uno is officially Uno line too. The confusing is that Uno-port line is just a nickname which is not widely used outside of JR West’s networ, for example in Tokyo.
Uno line, Okayama-Chayamachi-Uno opened in 1910. From Uno, JNR, Japan National Railway operated ferries between Uno and Takamatsu in Shikoku. Uno line and the ferry; Uko ferry was the major route for Japanese traveling between Honshu and Shikoku islands.
However, the ferry was abolished right after Seto-Ohashi bridge opened in 1988. JR constructed new line between Chayamachi-Kojima-Utazu, which is Honsh-Bisan line and direct through trains started operate between Honshu and Shinkoku. Most of the trains from Okayama continues to run on Honshi-Bisan line from Chayamachi. Which means passengers who want to travel to Uno or Naoshima island now have to change trains at Chayamachi.