Do not forget to take a "nude bath" when coming to Japan

There also is someone said that Onsen, like Sentou, is to bath very clean before soaking in the tub, except that it's done outdoor.

In fact, they are not the same, just a bit similar in form. Sentou is heated water being poured into the basin, while Onsen is natural hot springs formed by no longer or still active volcanoes. The water is pure mineral water, it's very good for health. Therefore, Japanese come to Onsen not only to relax or foster the spirit, but also for healing and body care.

Traditionally Onsen often left exposed (outdoor bath house in Japanese is rotenburo or notenburo), but nowadays indoor bathroom is very prevalent, operated under the management of local authorities or private sector (uchiyu) - usually hotel, ryokan or private inn (minshuku - only serves sleeping space and breakfast for guests), a characteristic of this kind of inn is that the owner often is landlady called okamisan.

Onsen mainly is in rural areas, so lovers, spouses and children or a whole company after a working day, or simply looking for a new and romantic place, take a train from the city to remote rural areas to relax and chat in the warm water.

Before soaking in the hot water, everyone would wash themselves clean with a shower, then get into the basin. In onsen bathing area there is a rule that visitors can't be dressed when taking a bath and should wear a thin kimono called yukata when moving to the bathtub.

Japanese people believe that communication in nude make people become more equal, empathetic and close, break down any barriers in position, title and occupation.

For foreign tourists, the tour instructor will explain very thoroughly about how to bath, dress and behave in the bathroom. Entering onsen space, one does not just lift off the costume, but also shed off all preconceptions about ethics and gender.

When the body is submerged in the hot steaming water with outdoor temperature below 10 degrees Celsius, the hand can touch trees' leaves, the nose can smell exotic flowers, the ear can hear river roaring like a waterfall - between human and human, human and nature there's no longer separation, even if it's just a thin layer of clothe or a little embarrassment.

Besides,  there also are additional services like: sauna, swimming pool, restaurant, motel... some become a resort with all kinds of services such as: meeting room, hotel, internet, tennis courts, table tennis, or even golf courts.