There used to be one in every neighborhood. Even in a city as large as Tokyo, there were many people who lived with a bathroom in their apartments (they did have a separate toilet, of course). So it was customary (and still exists today but to a far lesser extent) for young and older men (who lives alone or in worker's dormitories) to go to the local public bath. I used go too - to get clean and have a relaxing soak in the large
communal tube. But it was also very erotically stimulating to catch glimpses of all the scrubbing of backs, and chests, and the cleaning of cocks and assholes. It wasn't only one that I (or another guy who was also a little too eager or interested) got a semi hard-on while sitting across from another young stud - whose toned muscles were the results on many months of day labor. I love it best when 'buddies' would scrub each others' backs, or joke about the size of his own or poke fun at the 'large' size of his friend's dick.