Ô’u Honsen (Akita – Aomori) 　　 奥羽本線　（秋田―青森）

a1  Akayu     a2  Mamurogawa     a3  Yuzawa     a4  Hachirôgata     a5  Takanosu     a6  Ôwani Onsen

A  Zaô (Volcano)     B  Asahidake     C  Gassan (the highest of the 3 Dewa Mountains Hagurosan, Yudonosan, Gassan, significant pilgrimage spots associated with activities and beliefs linked to sacred mountains)   D  Chôkaisan (Volcano)     E  Iwakisan (Volcano)

The Ô'u Honsen was one of the major railway lines to the north, connecting Tôkyô with the plateau of Yamagata and, beyond it, the city of Akita, one of the main Japan Sea ports in northern Japan. From Akita northwards the Ô'u Honsen forms a link with the city and port of Aomori, from where ferries cross the Tsugaru Strait to Hokkaidô. The name "Ô'u　奥羽" refers on the one hand to the Province of Mutsu 陸奥 (basically present-day Aomori Prefecture), on the other hand to the two old provinces surrounding the 3 Dewa Mountains (出羽三山), namely Ugo 羽後 (basically present-day Akita Prefecture) and Uzen 羽前 (basically present-day Yamagata Prefecture).

Since the opening of the high-speed Shinkansen links to the north the Ô'u Honsen has lost much of its significance. Its southern part, the former 1067 mm gauge incline between Fukushima (71 metres above sea level) and Yamagata (136, 5 metres above sea level) via Yonezawa (248, 7 m.a.s.l.), was re-gauged to 1435 mm in 1991 to allow Shinkansen trains from Tôkyô to work through to Yamagata (services began on July 1, 1992). The continuation of 1435 mm gauge Shinkansen services through the Yamagata plateau as far as Shinjô was opened on December 4, 1999. From Shinjô northwards across the border into Akita Prefecture (Yuzawa – Yokote – Ômagari) there are only a few local trains per day.

The northern section of the Ô'u Honsen begins at Akita, 298, 7 km from Fukushima. At first it runs northwards through fertile rice growing country side, much of the way alongside the Hachirôgata reclaimed land. Hachirôgata was once a large lake and shallow lagoon; work transforming this lake into an area for intensive rice production was completed in 1977. Today only a few canals and retention basins are left. North of Hachirôgata trains arrive at Higashi Noshiro junction (56, 7 km from Akita), from where the spectacular and lonely Gonô-sen continues up the coast.

At Higashi Noshiro the Ô'u Honsen turns sharply inland to tackle the mountainous area, working up the river to the town of Ôdate (104, 2 km from Akita). On the way it passes through Takanosu junction, where the scenic Akita Nairiku Jûkan Tetsudô (The Railway through the Inner Part of Akita Prefecture) has its starting point. Beyond Ôdate the line cuts straight through the mountains. Since the laying of double track in 1971 one section here sees two separate track-beds, one for the up and one for the down line. As we approach the old castle town of Hirosaki (148, 4 km from Akita) vast fruit orchards, often apple orchards, catch the eye. Not far from the city rises the imposing Iwakisan volcano. Somewhat south of Hirosaki in the mountains lies Ôwani Onsen, where passengers can change to the local Kônan Tetsudô.

Beyond Hirosaki the line continues through agricultural land and several forests to Aomori, 185, 8 km from Akita. One station before Aomori is Shin Aomori, where the Shinkansen coming up from Tôkyô and continuing to Hokkaidô is met. At Aomori terminal the two traditional main lines to northern Japan – the east coast line Tôhoku Honsen and the west coast line Ô'u Honsen – come together. As both lines carry a considerable amount of freight there are extensive marshalling yards at Aomori, which until 1988 and the opening of the Seikan Railway Tunnel used to be the ferry port for travel to Hokkaidô.

As mentioned, freight trains over the northern section of the Ô'u Honsen from Akita to Aomori are frequent as the line is part of the freight link to the north from the Kansai area, passing through Tsuruga, Kanazawa, Niigata and Akita.

Building of the Akita to Aomori line began as early as 1894 and was completed by 1902. The line was electrified (AC 20 kV/50 Hz) in 1971. There is about 1 local service per hour between Akita and Ôdate, and between Hirosaki and Aomori. Services are less frequent between Hirosaki and Ôdate, particularly during daytime. The two cities of Akita and Aomori are also linked by 3 express trains a day.

The port area of Akita is served by two freight-only lines operated by the Akita Rinkai Tetsudou (5, 4 km and 2, 5 km long) and the branch line (2, 7 km) from Tsuchizaki (7, 1 km from Akita) to Akita Harbour (Akita-kô). This branch line has been regularly used since 2018 to meet cruise ships.