JR group is not the only railway company in Japan. There are dozens of private railway companies throughout Japan. Most of the non-JR group lines are for local commuters and foreign tourist hardly use them except subways. The biggest reason is that most of these lines are competing with JR lines which run near them. For example, most of the Japanese travel from Nagoya to Ise Jingu shrine using Kintetsu line but Japan Rail Pass holder will use JR Kansai+Ise railway line+JR Kisei main line+JR Sangu line from Nagoya. May be the frequently used by foreign tourists is Nankai Koya line which connects Osaka and Koyasan - UNESCO.
One of the private companies, Enoshima electric railway; Enoden is operating a single line called Enoshima dentetsu line between Kamakura station and Fujisawa station in Kanagawa prefecture. Dentetsu means abbreviation of electric railway in Japanese. Kamakura station is adjacent to JR Kamakura station of Yokosuka line and Fujisawa station is adjacent to JR Fujisawa and Odakyu Fujisawa stations.
Enoden is of course used by local commuters but there are many substantial numbers of tourists taking the Enoden. The biggest reason is that the Enoden is running near three major tourist destinations in Kanagawa prefecture. First major destination is Enoshima island. Then, second one is Kotokuin temple and third one is Hasedera temple. Especially Kotokuji temple is famous for foreign tourists for the big Buddha statue.
Enoshima dentetsu line is a single-track railway which is very uncommon in urban developed area, especially in Tokyo Metropolitan area. Also 6 stations do not have any staff allocated which is also rare. Unfortunately Japan Rail Pass is not valid but Suica and Pasmo are accepted.