Rias Line

The line's two original parts both began as Japanese National Railways (JNR) projects to serve the remote fishing communities of the Sanriku coast. In the south, the JNR Sakari Line opened from Sakari to Ayori (9.1 km) on 1 March 1970 and was extended to Yoshihama (12.5 km) on 1 July 1973. In the north, the JNR Miyako Line opened from Miyako to Tarō (12.8 km) on 27 February 1972 and the JNR Kuji Line from Kuji to Fudai (26.0 km) on 20 July 1975. The central stretch linking the two ends — Kamaishi to Miyako — was a separate corridor entirely: it had opened in stages in the 1930s as part of the Railway Ministry's Yamada Line and remained a JNR, and later JR East, route.

As JNR's finances deteriorated in the early 1980s these lightly used coastal lines were slated for closure. Rather than abandon them, Iwate Prefecture and the municipalities along the coast established the Sanriku Railway in 1981 as the first third-sector (joint public-private) railway company in the country. On 1 April 1984 Santetsu opened both of its lines at once. In the south it opened the South Rias Line from Sakari to Kamaishi (36.6 km): the former JNR Sakari Line was transferred and the new Yoshihama–Kamaishi section (15.0 km) opened to complete it. In the north it opened the North Rias Line from Miyako to Kuji (71.0 km), with the new Tarō–Fudai section (32.2 km) completing the route the JNR Miyako and Kuji lines had begun.

For a quarter of a century the two lines carried local passengers along a remote and scenic coast. That settled existence was shattered on 11 March 2011, when the Great East Japan Earthquake and the tsunami it generated struck the Sanriku coast. The entire Sanriku Railway network was suspended; across the two lines damage was recorded at roughly 300 locations, including station buildings and bridges, and the tsunami washed away some 5.8 km of track. The parallel Yamada Line between Kamaishi and Miyako was severed as well.

Sanriku Railway became one of the most visible symbols of the region's recovery, restoring service in stages from only days after the disaster. On the North Rias side the Rikuchū-Noda–Kuji section reopened on 16 March 2011, just five days after the earthquake, run as free 'recovery-support' trains; Miyako–Tarō followed on 20 March and Tarō–Omoto on 29 March, and after the Tanohata–Rikuchū-Noda section returned on 1 April 2012, the last gap, Omoto–Tanohata, reopened on 6 April 2014. On the South Rias side the Sakari–Yoshihama section (21.6 km) reopened on 3 April 2013 and the Yoshihama–Kamaishi section (15.0 km) on 5 April 2014. With those reopenings, full restoration of both of Santetsu's original lines was completed in April 2014.

That still left the two lines as separate pieces, divided by the gap at Kamaishi–Miyako where the tsunami-severed Yamada Line had run. Rather than restore that section itself, JR East rebuilt it and arranged to transfer it to Sanriku Railway. On 23 March 2019 the Kamaishi–Miyako section (55.4 km) was reopened and handed over, and with it the North Rias Line, the transferred ex-Yamada section, and the South Rias Line were knitted together into a single continuous route branded the Rias Line. Regular through services over the line began the next day, 24 March 2019.

The unified Rias Line now runs the full 163.0 km from Sakari to Kuji, its three constituent parts surviving as operating sections within the whole: Sakari–Kamaishi (the South Rias Line, 36.6 km), Kamaishi–Miyako (the former Yamada Line, 55.4 km) and Miyako–Kuji (the North Rias Line, 71.0 km). Most trains run within a single section; only one service each way per day traverses the entire line. Diesel railcars thread the rugged, ria-indented coast that gives the line its name, and the route remains a lifeline for the coastal communities of Iwate and an enduring emblem of the Sanriku region's recovery.

• 19701 March: JNR opens the Sakari Line from Sakari to Ayori (9.1 km), the first part of what becomes the South Rias Line.
• 197227 February: JNR opens the Miyako Line from Miyako to Tarō (12.8 km), the first part of what becomes the North Rias Line.
• 19731 July: the JNR Sakari Line is extended from Ayori to Yoshihama (12.5 km).
• 197520 July: JNR opens the Kuji Line from Kuji to Fudai (26.0 km); the central Tarō–Fudai gap is still under construction.
• 1981Iwate Prefecture and coastal municipalities establish the Sanriku Railway, the first third-sector railway company in Japan, to take over the JNR lines slated for closure.
• 19841 April: Sanriku Railway opens the South Rias Line, Sakari–Kamaishi (36.6 km) — the former JNR Sakari Line is transferred and the new Yoshihama–Kamaishi section (15.0 km) opens.
• 19841 April: Sanriku Railway also opens the North Rias Line, Miyako–Kuji (71.0 km) — the former JNR Miyako and Kuji sections are transferred and the new Tarō–Fudai section (32.2 km) completes the route.
• 201111 March: the Great East Japan Earthquake and tsunami suspend the entire Sanriku Railway network; across the two lines damage occurs at ~300 locations and about 5.8 km of track is washed away. The parallel Yamada Line (Kamaishi–Miyako) is also severed.
• 201116 March: only five days after the disaster, the North Rias section Rikuchū-Noda–Kuji reopens as free 'recovery-support' trains; Miyako–Tarō follows on 20 March and Tarō–Omoto on 29 March.
• 20121 April: the North Rias section Tanohata–Rikuchū-Noda reopens, leaving Omoto–Tanohata as the last closed gap.
• 20133 April: the South Rias section Sakari–Yoshihama (21.6 km) reopens.
• 2014April: full restoration of both original lines is completed — the North Rias section Omoto–Tanohata reopens on 6 April and the South Rias section Yoshihama–Kamaishi (15.0 km) on 5 April.
• 201923 March: the rebuilt Yamada Line section Kamaishi–Miyako (55.4 km) is reopened and transferred from JR East to Sanriku Railway, joining the North Rias, ex-Yamada and South Rias sections into a single through Rias Line.
• 201924 March: through services begin over the unified Rias Line — 163.0 km, 41 stations, Sakari to Kuji — comprising Sakari–Kamaishi (South Rias, 36.6 km), Kamaishi–Miyako (ex-Yamada, 55.4 km) and Miyako–Kuji (North Rias, 71.0 km).