Keihan Nakanoshima Line

The line was conceived to relieve congestion at Yodoyabashi, the long-standing western terminus of the Keihan Main Line, and to give Keihan a foothold in the office districts of Nakanoshima that the Osaka subway network did not directly serve. Trains run through onto the Keihan Main Line rather than terminating, and within the Nakanoshima Line every service stops at all stations. The formal starting point is Nakanoshima, but in operating terms trains running from Temmabashi toward Nakanoshima are treated as "down" services and the reverse direction as "up."

Planning for a Nakanoshima line dates back to around 1980, when Keihan studied it as a way to enable ten-car operation on the Main Line, ease crowding at Yodoyabashi, and connect with projected lines such as the Katafuku connecting line (later the JR Tozai Line) and the Naniwasuji Line. The project took concrete form at the start of the 2000s: Keihan formally decided to proceed in March 2001, and the Nakanoshima High Speed Railway Company was established in July 2001 to own the infrastructure as a third-sector enterprise, with Keihan as the operating railway. An application for project authorisation followed in September 2001, and Osaka's city planning council recommended the scheme in October 2002.

Construction began with a groundbreaking ceremony held at the Osaka International Convention Center on 28 May 2003. The line was driven entirely underground beneath the rivers and streets of Nakanoshima, and the tunnel between Temmabashi and Naniwabashi was lined with ductile-iron segments because the active Uemachi Fault crosses that section; watertight doors were also installed where the route passes beneath the Tosabori River. The tunnel was holed through along its whole length on 31 October 2007, the rails were joined in March 2008, and after fares were approved that April, driver-training test runs began on 1 August 2008.

The Keihan Nakanoshima Line opened between Nakanoshima and Temmabashi on 19 October 2008. Three of its four new stations — Naniwabashi, Oebashi and Nakanoshima — were built in an area without subway coverage and so, unlike the Main Line's Yodoyabashi and Kitahama, they do not connect directly to the Osaka Metro; only Watanabebashi links underground to the network, at the Yotsubashi Line's Higobashi. To work the line Keihan introduced the 3000 series, used on a newly created Rapid Express service that initially ran through to Demachiyanagi at thirty-minute intervals during the day.

Ridership fell well short of expectations. The pre-opening forecast of about 72,000 passengers a day was never approached, and combined daily boardings and alightings at the four new stations have hovered around the low-to-mid 20,000s — roughly 25,600 in fiscal 2008 — a shortfall attributed to the small number of connecting lines and the absence of major shopping districts along the route. Keihan responded with a succession of timetable reductions: a first cut came in September 2009, daytime Rapid Express and Semi-Express services were withdrawn in May 2011, and in September 2021 the daytime frequency was reduced from six to four trains an hour.

More recent changes have included the start of K-ATS automatic train stop operation in January 2021, a March 2025 revision that shortened many daytime local and semi-express trains to four cars and added special Limited Express and Rapid Express services during the 2025 Osaka-Kansai Expo, and the introduction of one-man operation on four-car trains from October 2025. Keihan has long wished to extend the line westward from Nakanoshima toward Nishikujo and the Yumeshima area; a 2004 regional transport council report proposed a Nakanoshima–Nishikujo–Shin-Sakurajima alignment, but after years of study a Nakanoshima–Kujo route was judged the stronger option in 2025, with Nakanoshima Station also planned as an interchange with the future Naniwasuji Line.

• 200130 March: Keihan Electric Railway formally decides to undertake the Nakanoshima New Line project; on 10 July the Nakanoshima High Speed Railway Company is established as the third-sector infrastructure owner.
• 200127 September: Keihan and Nakanoshima High Speed Railway apply for authorisation of the Nakanoshima New Line.
• 20029 October: the Osaka City Planning Council recommends the Nakanoshima New Line to the city.
• 200328 May: a groundbreaking ceremony is held at the Osaka International Convention Center and construction begins.
• 200613 November: the official line name and station names are announced (replacing the provisional working names).
• 200731 October: the tunnel is bored through along its entire length.
• 20081 August: driver-training test running begins on the new line.
• 200819 October: the Keihan Nakanoshima Line opens between Nakanoshima and Temmabashi (3.0 km), with through-running onto the Keihan Main Line and a new daytime Rapid Express worked by 3000 series trains.
• 200912 September: a first timetable change reduces Nakanoshima Line services, switching some rush-hour express trains to start and end at Yodoyabashi instead.
• 201128 May: a timetable revision discontinues the daytime Rapid Express and Semi-Express, leaving a daytime pattern of two Sub-Express and four Local trains per hour.
• 201316 March: a timetable revision converts most daytime Sub-Express trains to Locals and withdraws the Katano Line through services 'Orihime' and 'Hikoboshi'.
• 20141 April: station numbering is introduced on the line (Nakanoshima KH54 to Temmabashi KH03).
• 20219 January: K-ATS automatic train stop comes into use on the line.
• 202125 September: as Keihan moves daytime services to a 15-minute base interval, the Nakanoshima Line's daytime frequency is cut from six to four trains per hour.
• 202522 March: a timetable revision shortens many daytime Local and Semi-Express trains to four cars; special Limited Express and Rapid Express services run during the Osaka-Kansai Expo.
• 202526 October: one-man (driver-only) operation begins on four-car trains.