Sento/Onsen with Young People in Osaka

So I heard that only older people use onsen/sento in Japan nowadays? Which ones in Osaka have more young people that go?

There is the one near Tennoji. Spa world. A number of baths and spas each with their own theme. E.g. roman. turkey, sand, cave, rock

I went to Suminoe two years ago as it was included with the Osaka Amazing Pass.

http://www.spasuminoe.jp/index.html
https://www.osaka-info.jp/osp/en/pdf/guide.pdf

It was a (very late) Friday night and I found people of all ages, at least in the male section. I can also remember a pack of guys in their middle twenties having a bath.

If you go, please be very careful when you pass the main door, as you have to take off your shoes even before reaching reception; it is advised on a small poster which is so easily missable that you could end so embarrassed as I did.