That's pretty wild. No shower or bath? I've yet to enter a place like that in Japan. The pictures in this post are of a sentou that is right around the corner from my house. I often pass it while taking my kids for walks and I've never seen young people entering or leaving it. I often wonder why people still use it, but I imagine it has to do with old habits and maybe even social rituals for the elderly people living in my neighborhood.
I enjoy going to the bathhouses here too, but when I go to them, I often go to larger and newer ones across town that have a variety of pools and relaxation rooms, etc. The sentou I frequent the most is always full of kids and families. The one in my neigborhood, like I said, never seems to be.