You can believe whatever you like. As I said it was over ten years ago and I suspect the term "sento" was not widely used when describing Japanese bathing facilities to tourists back then.The term sento has always been used for them. Given you do not know the difference between the two suggests to me that you have never been there ever. Even greater than ten years ago the term sento was always used. Onsen is an entirely different product.
You continue to try to twist my words instead on admitting that your inital post was not correct and that my following post clarified the issue.
Alessandra has kindly explained the Izumu procedure which confirms my comment. Thank you Alessandra.
Over and out!
The sento (Japanese bath house) is a facility for cleaning.