Gantoku-sen 岩徳線
Diesel car class KIHA 40 no.2123 at the crossing point Suô Kubo. (2015)
This line actually forms the direct connection between the towns of Iwakuni and Tokuyama and could be considered as part of the San'yô Honsen. However, as the Gantoku-sen has steep gradients and several long tunnels (the longest one, between Hashirano and Kinmeiji, is 3149 m long), the San'yô Honsen between Iwakuni and Tokuyama takes the much longer route along the coast and through the town of Yanai. In contrast to this longer route, the Gantoku-sen is only single track and not electrified. It is 43, 7 km long from Iwakuni in the east to Kushigahama in the west, but trains run through for another 3, 4 km over the San'yô Honsen into the town of Tokuyama.
The Gantoku-sen serves a very rural area through the mountains of the old province of Suô; just east of Tokuyama there is some suburban traffic, as Tokuyama's residential area is located in the hills at some distance from the huge industrial complexes (oil and chemical industry) around the city and in the port area. Almost throughout, the Gantoku-sen follows the San'yô Shinkansen line, which cuts directly through the mountains between the Iwakuni region and Tokuyama; however, as long stretches of the Shinkansen are in tunnels, the high-speed line is only visible from time to time from Gantoku-sen trains.
Seen from the west, the Gantoku-sen at its eastern end (at Morigahara signal, 7, 5 km from Iwakuni) merges with what used to be the Gannichi-sen, a line constructed 1960-1963 with the intension of forming a link between Iwakuni and the Japan Sea via a junction with the Yamaguchi-sen at Nichihara. However, work on the Gannichi-sen was stopped at Nishiki-chô, some 32, 7 km up the valley, and in 1987 this stub became the private Nishikigawa Tetsudô, following the river Nishikigawa. Since then, Nishikigawa Tetsudô trains coming down from Nishiki-chô work over the Gantoku-sen from Morigahara signal into Iwakuni (and vice versa).
Services on the Gantoku-sen are mostly provided by a single diesel car, and at certain times of the day by two or three car trains. There are 12 to 13 trains per day, which stop at all stations. Freight services ended in 1974.
The Gantoku-sen was built 1929-1934, and it takes its name from the two characters standing for Iwakuni (岩国) and Tokuyama (徳山), together (岩徳) read "Gantoku".
On July 6, 2018, the line suffered enormous damage due to landslides in the wake of torrential rainfall. Complete reopening was on September 23, 2018.