The 115 series is a DC electric multiple unit (EMU) train type developed by Japanese National Railways (JNR) and now operated by West Japan Railway Company (JR-West), and the Shinano Railway.

The Shōnan–Shinjuku Line is a passenger railway service in Japan which commenced in December 2001. The line has no dedicated track as services run through shared sections along the Ryōmō Line, Takasaki Line, Utsunomiya Line, Yamanote freight line, Yokosuka Line, and Tōkaidō Main Line. It is treated as a distinct service at stations and on railway maps.