The Sangi Railway Hokusei Line is one of two remaining 762mm special narrow gauge commuter train lines. The second is the Yokkaichi Asunarou Railway Utsube Line. Both lines were previously part of the Kintetsu Railway group. The Kurobe Gorge line is also 762mm gauge.
Sangi Railway Hokusei Line https://en.wikipedia.org/wiki/Sangi_Railway_Hokusei_Line
Yokkaichi Asunarou Railway Utsube Line https://en.wikipedia.org/wiki/Yokkaichi_Asunarou_Railway_Utsube_Line
A look at the Yokkaichi Asunarou Railway. Video by masanaga.
A look at the Sangi Railway Hokusei Line first. Video by ananyuso