The 155 series (155系) was an electric multiple unit (EMU) train type operated by Japanese National Railways (JNR) from 1959 until 1983.

[1] They were originally designed for and used on school excursion trains running between Tokyo and the "Keihanshin" Kyoto/Osaka/Kobe area via the Tokaido Main Line.

[2] The trains were initially painted in what was to become the standard JNR excursion train livery of "lemon yellow" and "light scarlet" selected from colour schemes proposed by 313 different junior high schools in the Tokyo and Keihanshin areas.

[2] The 155 series trains underwent refurbishment and repainting into the Shonan livery of orange and green from 1973, and the former Kansai area sets were transferred to Ogaki Depot in 1974 for use on "rapid" limited-stop services and charter train services.

[2] The Tamachi-based Tokyo area sets saw use on school excursions to Nikko, and winter season trains to ski resorts in the Joetsu region.