A ride on the Hakone Tozan Railway (箱根登山電車, Hakone Tozan Densha), Japan's oldest mountain railway, is a treat for more than just railway fans. The small trains wind themselves through a narrow, densely wooded valley over many bridges and tunnels, stopping at small stations along the way and changing directions at three switchbacks.

The Hakone Tozan Line consists of two sections. The lower section from Odawara to Hakone-Yumoto is used by Odakyu trains from central Tokyo and is not particularly noteworthy. Far more spectacular is the upper section from Hakone-Yumoto to Gora, which is served by the small mountain trains. At Gora, many travelers transfer to the cablecar for Lake Ashi.

The 35 minute train ride from Hakone-Yumoto to Gora is especially beautiful in June and July when thousands of hydrangea (ajisai) are in bloom along the tracks and are illuminated during the evenings. The ajisai are usually best around the beginning of July and can be seen from the trains and around the stations.

Special trains run from mid June through mid July between Hakone-Yumoto and Gora Stations for the viewing of the illuminated flowers. They depart in the evenings, twice in each direction, and require seat reservations.