In a quiet residential area of Tokyo's Bunkyo Ward, half hidden by a large maple tree, stands an impressive, castlelike wooden structure that is like a portal to another time. With old-fashioned kawara tiles on its pagoda-style roof, and its curliculed surrounding stone wall, the building is evocative of an era when yukata and geta were common and people called places like this home.

Outside the building, the sound of chatter and occasional laughter floats out of the windows. Just inside the door, patrons are greeted with a cloud of steam and the pleasant scent of soap. This is Tsuki no Yu, one of the oldest sento(public baths) in Japan. Built in 1933 by miyadaikucarpenters who specialized in temples and palaces, it stands as grandly today as it did when its doors first opened.

Just as customers do at many sento throughout the country, people sit in Tsuki no Yu's washing area on low stools, shampooing their hair and scrubbing their bodies before simmering in the deep baths kept at around 40-43 C. In the changing rooms, others lie relaxing on the floor, towels strategically placed, or sit on rattan chairs chatting away with their faces flushed from the hot steamy bath.

Unlike more modern sento, however, Tsuki no Yu provides no other diversion than that offered by the other patrons. This is deliberate. Sento are traditionally places where people in the community can converse with one another -- even with strangers -- and the management here would like to preserve the original atmosphere of the sento as well as the original structure.

Indeed, for many people of the older generation, sento are an integral part of a valuable community hub.

"In a sense, sento are an important part of Japanese culture," says Yasue Yamada, the 57-year-old owner, whose family has run Tsuki no Yu for generations. "We must do everything we can to preserve this fading custom.

"The only change we have made was adding two more rows of tiles to the wall dividing the men's and women's bathing rooms, since people's average height has gone up considerably."

Historians believe that the concept of bathing arrived in Japan with Buddhism, sometime early in the sixth century. However, it wasn't until the common people's culture began to blossom in the early Edo Period (1603-1867) that the sento business really took off. Back then, men in particular took to these new facilities with gusto, perhaps in part because of the back-washing services offered at certain establishments by women called yuna. Because back-washing soon degenerated into prostitution, the government banned these brothel-bathhouses in 1657, but this didn't kill the tradition of sento.

At their peak in 1964, sento numbered 23,016 nationwide. Since then, though, the advent of uchiyu (built-in-baths) in many newly constructed homes and apartments has hit the bathhouse business hard. Furthermore, longer workdays made it difficult for many people to get to a sento in time to relax for an hour or so before closing time. As a result, by 1999 the total number of sento had dropped to just 8,422.

As well as these factors, the emergence of supasento has also contributed to the decline of old-school sento. With their state-of-the-art facilities and flashy interiors, these establishments attract people from all age groups. Some traditional bathhouses, whose customers tend to be older members of the community, have even made the switch to supasento. Yamada, however, remains positive. "At first glance, they may seem to be hurting our business, but actually, they're not," she says. "Supasento are purely for leisure on special occasions, whereas sento directly serve the needs of people's daily lives." This is certainly true for Hanako Morioku, a 79-year-old longtime regular at Tsuki no Yu. Even though she has her own bath at home, Morioku goes to the sento every day.

"I come here because I feel completely refreshed after taking a bath in such a big tub with my neighborhood friends," she says. "The sento is not just a place for bathing, it's also a place for communication, a chance to reach out to others in the community."

This is precisely what makes this business rewarding for Yamada. "People come in with their heads down from stress, but leave saying they'll be back, looking refreshed and wearing smiles on their faces. That is what keeps me going."