All rail infrastructure should be mapped, even streetcar tracks. Tokyo is full of subway-like lines (in light-blue) so at first glance it doesn't seem like many

All rail infrastructure should be mapped, even streetcar tracks. Tokyo is full of subway-like lines (in light-blue) so at first glance it doesn't seem like many are missing. This is based on OSM data, so the definition on the wiki should be used: https://wiki.openstreetmap.org/wiki/Tag:railway%3Dsubway https://wiki.openstreetmap.org/wiki/Tag:railway%3Dsubway (which isn't very specific).