I don't know how long these have been around--probably for thousands of years--but I just recently discovered them. They're called ashi-yu (足湯) which literally translates as "foot hot water". But I guess a hot footbath describes them well enough. They seem to be at all the train stations these days. Even our little rinky-dink station got one not too long ago.
Yesterday we left early and spent all day walking around Mount Fuji (those pictures later). We got in around six or so and were actually heading to one of those izakayas we particularly like, when we discovered it was closed. The little ashi-yu place was free and since our dogs were really barking we all stopped to enjoy that instead. There's J (green shirt) fixin' to put his socks back on and his buddy S coming down the mini stairs.
So how you work one of these is pretty simple. You simply remove shoes and socks, roll up pants if you're me or someone like me. And insert footsies in to the obscenely hot water.
Here is a close up. You can see by S's face...I joke not when I say it is obscenely hot. It feels absolutely wonderful!