Public bathing at the hot springs or onsen is by no means a recent phenomenon in Japanese culture. References in the kogiji—the oldest extant chronicle in Japan—show that Japanese have been bathing in the hot springs for well over a thousand years, and there are many historical accounts of feudal lords having their own favourite onsen spots (kakushi-yu) where they may have let their samurai bathe after battle (the onsen has long been known for its healing qualities). During the Edo period, as the checkpoints and barriers that had previously prevented the exchange of information and people from one domain to another began to vanish, rumors about where to find the best hot springs began to spread. Citizens began to travel outside their own area to onsen regions such as Yamanashi and Niigata, leading to the onsen culture that we know in Japan today.
There remains an abiding image both in Japan and abroad that you need to travel to the mountainous regions of the country to experience the hot springs. In fact, while regional Japan does have some of the most famous and photographed onsen, there are many traditional establishments located in and near Tokyo that offer an equally good glimpse into the ubiquitous culture of public bathing. Some good examples include Yumori no Sato in Chofu and Shiraku no Yu in Kanagawa.
For some foreign visitors the idea of stripping down and bathing with others might not be the most natural thing to do, but armed with a little knowledge about the customs and etiquette in the onsen there’s no reason not to enjoy this significant part of Japanese culture, and the many different baths in which you can soak your bones.
One common question is regarding tattoo policy at the day onsen. Unfortunately, many establishments have a strict policy of denying entry to anyone with body markings, but if the tattoo isn’t too conspicuous you should be able to use the onsen if you cover it up.