Japanese Sentō bathhouses have their origins in the Buddhist Temples of India.
Initially a strictly religious affair, priests used yūya 湯屋 (hot water shops) for cleanliness. Eventually the sick and unwell were also allowed to make use of the baths and wealthy citizens began to have private facilities installed in their homes.
Over several years public Sentō grew in popularity, somewhat aided by the addition of female bathing attendants who would perform additional ‘services’ beyond the bathhouse, eclipsing the religious notions on which they were founded.
In more recent history the tattoo-clad Yakuza held secret meetings in Sentō to such an extent that many bathing establishments banned anyone with tattoos for fear they were gang members.
Although we want to attain all the benefits brought on by a good bath, we don’t think you should have to risk stumbling upon a criminal plot. Get all the benefits of bathing from the comfort (and safety) of your home.