These are relatively easy to find in Japan
Couldn’t tell you why but they are
Despite the old stereotype of Japan being a futuristic nation that produces the technology of tomorrow, a lot of it’s institutions are still using very outdated technology.
Fax is still very actively used
Read one time that “thirty years ago, Japan was ten years in the future. Today, Japan is twenty years in the past.”
Pay phones are still common in many places around the world. An indicator may be those mapped on OSM: https://taginfo.openstreetmap.org/tags/amenity=telephone#map
They are common in my country, but I hardly ever see anyone use them.
Open it.
Those green guys were everywhere when I’ve been, they look so satisfying