大村線
On 24 March 1934, a track was opened from Isahaya to , known as the Ariake Nishi, as part of the development of an alternative route for the Nagasaki Main Line along the coast of the Ariake Sea. By 1 December 1934, a link up was achieved between the Ariake Nishi Line at Yue and the Ariake Higashi Line which had been extended south from to . The Ariake Nishi and Ariake Higashi Lines were then designated as part of the Nagasaki Main Line. The line from Haiki to Isahaya was separated to become the Ōmura Line.