The Tateyama Tunnel Trolleybus (立山トンネルトロリーバス, Tateyama Tonneru Tororībasu), officially the Trolleybus Line (無軌条電車線, Mukijō Densha-sen), is a Japanese trolleybus line in Tateyama, Toyama, operated by the Tateyama Kurobe Kankō Company. The line is entirely underground (in tunnel), including both termini. It is the last remaining trolleybus line in Japan with the conversion of the Kanden Tunnel Trolleybus line to battery operation in November 2018.[1] It is also the last remaining right-hand drive trolleybus line in the world. The line is a part of the Tateyama Kurobe Alpine Route. The line originally opened as a normal (diesel) bus line in April 1971,[2] but was later re-equipped for trolleybuses. The trolleybus line opened on 23 April 1996.[3]