The Kosei Line is a commuter rail line in Osaka-Kobe-Kyoto Metropolitan Area, operated by West Japan Railway Company. The line was completed in 1974 by the former Japanese National Railways (JNR) to provide faster access from the Kansai region to the Hokuriku region. It originates at Yamashina Station in Yamashina-ku, Kyoto and ends at Ōmi-Shiotsu Station in Nagahama, Shiga.

The West Japan Railway Company, also referred to as JR West , is one of the Japan Railways Group companies and operates in western Honshu. It has its headquarters in Kita-ku, Osaka. It is listed in the Tokyo Stock Exchange, is a constituent of the TOPIX Large70 index, and is also one of only three Japan Railways Group constituents of the Nikkei 225 index: the others are JR East and JR Central. It was also listed in the Nagoya and Fukuoka stock exchanges until late 2020.