@@Japanese people do not use baths just to wash themselves; they also
like to warm themselves by soaking slowly in a deep tub full of hot water.
The actual washing and rinsing is done outside the tub. Baths are constructed
to allow the water in the tub to be heated directly, so when the level
of hot water drops, it is topped up with cold water and reheated. A number
of people use the same bath in turn, and the tub is emptied after the last
person finished.
(From "Nippon-The Land and Its People-"written by Nippon Steel
Resources Development, published by Gakuseisha Publishing Co.,Ltd.)