Seikibashi Line

Every Seikibashi Line car runs through onto the Higashiyama Line to terminate at Okayama Station, so the route effectively functions as a city-centre extension of the network rather than a self-contained line. Service runs at roughly ten-minute intervals, and the journey from the Okayama Station forecourt to Seikibashi takes about twelve minutes when traffic permits. Because the two routes share track north of Yanagawa, the line numbering counts the Okayama Station stop as S01, with the Seikibashi Line proper carrying the stop numbers S03 through S09.

The line opened on 18 March 1928 as the Yanagawa Line, built to carry visitors to the third venue of the Dai-Nippon Industrial Exhibition held in Okayama that year; the original section ran from Yanagawa to Daiunjichō. Over the following years its stops were added to and repeatedly renamed: Higashi-Tamachi opened in 1931 and became Yūbinkyoku-mae ("in front of the post office") in 1937, while the Renshōji-mae stop was renamed Shiyakusho-mae ("city hall front") in 1942.

The defining change came on 6 September 1946, when a new section was opened from Daiunji-mae to Seikibashi while the older stretch between Shinsaidaijichō-suji and Daiunjichō was abandoned, shifting the southern end of the route to its present alignment. With this extension the line was renamed the Seikibashi Line, the name it still carries. Station renamings continued thereafter — Shiyakusho-mae became Chūtetsu Bus-mae in 1954 and then Tamachi in 1985 — and the little-used Suriyamachi-suji stop was abolished in 1967.

Okayama Electric Tramway had also held a licence to push the line beyond Seikibashi as far as Toyonari, but the extension was never built and the concession lapsed in 1960. The route therefore settled into its 1.6-kilometre form, threading through the dense commercial heart of Okayama past the city's main shopping arcades, department stores, banks and the central post office, and reaching Okayama University's Shikata campus and university hospital at the southern terminus.

Major reconstruction of the corridor accompanied the building of a common utility duct beneath Yanagawa-suji, carried out in two phases. During the works the tracks were temporarily shifted to the side of the road, a "side reservation" arrangement rarely seen in Japan, and at the same time the track centres were widened. The result is that the whole line is now supported by centre poles — set in the central median between Yanagawa and Daiunji-mae — and every stop except Seikibashi has an island platform.

Accessibility was upgraded in step with new rolling stock. When the low-floor 9200 series "MOMO" tram was introduced in 2002, all stops except Seikibashi were made barrier-free, with ramps added and platforms lengthened, and a roof was provided at Yūbinkyoku-mae. A new intermediate stop, Higashi-Chūōchō, opened between Daiunji-mae and Seikibashi on 3 August 2007, built barrier-free from the outset. Seikibashi itself was comprehensively rebuilt and made barrier-free in August 2007, with a new pedestrian crossing on its south side following that November. A timetable revision on 20 July 2012 cut the basic interval from nine to ten minutes.

• 192818 March: opens as the Yanagawa Line between Yanagawa and Daiunjichō, built to carry visitors to the third venue of the Dai-Nippon Industrial Exhibition in Okayama.
• 19311 September: Higashi-Tamachi stop opens, between Suriyamachi-suji and Renshōji-mae.
• 19376 July: Higashi-Tamachi stop is renamed Yūbinkyoku-mae.
• 194223 June: Renshōji-mae stop is renamed Shiyakusho-mae.
• 19466 September: the Daiunji-mae–Seikibashi section opens while the Shinsaidaijichō-suji–Daiunjichō section is abandoned; the route is renamed the Seikibashi Line.
• 195411 August: Shiyakusho-mae stop is renamed Chūtetsu Bus-mae.
• 1960The licence to extend the line beyond Seikibashi to Toyonari lapses, the extension never having been built.
• 1967The little-used Suriyamachi-suji stop is abolished (exact date unknown).
• 19851 July: Chūtetsu Bus-mae stop is renamed Tamachi.
• 20073 August: Higashi-Chūōchō stop opens between Daiunji-mae and Seikibashi, built barrier-free from the outset; Seikibashi itself is rebuilt barrier-free the same month, with a new crossing on its south side added in November.
• 201220 July: a timetable revision lengthens the basic service interval from nine to ten minutes.