The Mt. Fuji is a "Romancecar" limited express train operated by Odakyu Electric Railway between Shinjuku and Gotemba via the Odakyu Odawara Line and JR Central's Gotemba Line.

The Romancecar is Odakyu Electric Railway's name for its limited express luxury tourist services south-west of Tokyo, to mountain resorts such as Hakone and Gotemba, and beaches such as Odawara and Enoshima. When the service started in 1957 with the 3000 series SE trainset, it broke the world speed record for a narrow gauge train. This record gave impetus for the design of the first Shinkansen, the 0 series. The 50th anniversary of the Romancecar's narrow gauge world speed record was celebrated September 28, 2007. Some of the latest designs incorporate regenerative braking.