Sentō
Tsurusawa Monzaemon had the idea for modern sentō in 1878.  Instead of a steam bath, he built a big tub that the bather could sit down in.  He put windows in his sentō so there would be light to see by.  This made it easier to see whether the water was clean.  People liked these new sentō and soon built many more of them.  In 1885, the government said no one could build the old, dark sentō any more.  All new sentō had to be light so they could be kept clean.  They also passed a law against men and women bathing together, but no one cared about it until after many foreigners began to visit Japan later in the Meiji period (late 1800s).