Renraku Line

The connecting segment exists only because of the way Matsuyama's tram lines were knitted together over the twentieth century. The relevant alignment belongs historically to the Jōhoku Line, whose Kiyamachi–Ichiman section (Ichiman is today's Kamiichiman) opened on 3 April 1927. At Ichiman the Jōhoku Line met the Jōnan Line, and in the original layout the junction faced the Dōgo Onsen direction of the Jōnan Line, with through running toward the Minami-horibata side and onto the Jōhoku Line.

The decisive change came on 1 December 1969, when Iyotetsu introduced circular (loop) operation linking the Jōhoku and Jōnan lines. A new stop, Heiwa-dōri 1-chōme, was opened, and the short Jōhoku Line section between Heiwa-dōri 1-chōme and Kamiichiman was abolished and immediately re-laid. The junction at Kamiichiman was reoriented so that the connection to the Jōnan Line faced the Keisatsusho-mae (police-headquarters) direction rather than the Dōgo Onsen direction. In the railway statistics of the time, this re-laid 0.1 km stretch was recorded not as its own line but as a branch of the Jōnan Line.

For nearly half a century the segment carried no distinct name of its own, appearing in official records merely as that Jōnan Line branch. That changed administratively in 2018: beginning with that year's edition of the Railway Handbook (Tetsudō Yōran), the government's standard register of Japanese railways, the Heiwa-dōri 1-chōme to Kamiichiman section was split out from the Jōnan Line and listed independently under the name 'Renraku Line'. The line's physical form did not change — the renaming simply gave a long-standing connecting track its own entry.

In service terms the Renraku Line is invisible to most riders, because no train is operated as a 'Renraku Line' service. Instead the whole of its 0.1 km is traversed by Iyotetsu's two circular tram routes: the No. 1 (clockwise) loop and the No. 2 (anti-clockwise) loop, which together trace a ring through central Matsuyama past Matsuyama City Station, JR Matsuyama Station, Kiyamachi, Teppōchō and Ōkaidō. The line is single-track throughout and uses a special automatic block system of the trolley-contactor type. Its rolling stock is shared with the rest of the Matsuyama city tram network and based at the Komachi rolling-stock works.

The line has just two stops, both in Matsuyama: Heiwa-dōri 1-chōme at the 0.0 km point, where it connects with the Jōhoku Line, and Kamiichiman at 0.1 km, where it connects with the Jōnan Line. Tiny as it is, the Renraku Line is a clear illustration of how Japan's tram networks are catalogued: a piece of track barely a hundred metres long is treated as a formally distinct line in the national railway register, precisely because it is the hinge that lets Matsuyama's loop trams keep circulating.

• 189522 August: the Jōhoku Line — the line on whose alignment the future connecting segment lies — originally opens (its Kiyamachi–Ichiman section follows later).
• 19273 April: the Jōhoku Line's Kiyamachi–Ichiman section (Ichiman is today's Kamiichiman) opens and meets the Jōnan Line at Ichiman, the junction facing the Dōgo Onsen direction.
• 19691 December: circular operation of the Jōhoku and Jōnan lines begins; Heiwa-dōri 1-chōme stop opens; the Jōhoku Line's Heiwa-dōri 1-chōme–Kamiichiman section is abolished and re-laid as a branch of the Jōnan Line, the Kamiichiman junction reoriented toward the Keisatsusho-mae direction.
• 2018From this year's edition of the Railway Handbook (Tetsudō Yōran), the Heiwa-dōri 1-chōme–Kamiichiman section is separated from the Jōnan Line and listed independently under the name 'Renraku Line'.