The Tosa Kuroshio Railway Asa Line is a 42.7 km Japanese railway line operated by the third-sector railway operator Tosa Kuroshio Railway. It connects Gomen Station in the city of Nankoku with Nahari Station in the city of Nahari in Kōchi Prefecture. The line is also commonly known as the Gomen-Nahari Line (ごめん・なはり線).

Dosan Line is a railway line in Shikoku, Japan, operated by the Shikoku Railway Company. It connects Tadotsu Station in Tadotsu, Kagawa, and Kubokawa Station in Shimanto, Kōchi. The line links the city of Kōchi with northern Shikoku and the island of Honshū via the Seto-Ōhashi Line. The first section of the line between Tadotsu and Kotohira opened in 1889, Kochi was connected to the northern section of the line in 1935, and the western extension of the line was completed in 1951. The name of the line comes from "Tosa" (土佐) and "Sanuki" (讃岐), the old provincial names of present-day Kōchi Prefecture and Kagawa Prefecture, respectively.