In Japan, are hot springs and the bathing facilities and traditional inns around them. There are approximately 25,000 hot spring sources throughout Japan, and approximately 3,000 establishments use naturally hot water from these geothermally heated springs.
' may be either or . Traditionally, were located outdoors, although many inns have now built indoor bathing facilities as well. Nowadays, as most households have their own baths, the number of traditional public baths has decreased, but the number and popularity of have increased since the end of Second World War. Baths may be either publicly run by a municipality or privately, often connecting to a lodging establishment such as a hotel, ryokan, or minshuku.
The presence of an is often indicated on signs and maps by the symbol â¨, the kanji (yu, meaning "hot water"), or the simpler phonetic hiragana character ã (yu).
According to the Japanese , is defined as "hot water, mineral water, and water vapor or other gas (excluding natural gas of which the principal component is hydrocarbon) gushing from underground". The law states that mineralized hot spring water that feeds an must be at least originating at a depth of at least , and contain specified amounts of minerals such as sulphur, sodium, iron, or magnesium.Even if it does not meet this definition, if the spring water is suitable for bathing, it is considered a "hot spring" in most cases. However, in that case, there are restrictions on the health benefits that the owner of the spring can claim.
When water contains distinctive minerals or chemicals, establishments often display what type of water it is, in part because the specific minerals found in the water have been thought to provide health benefits. Types include , , , and .
Exactly when humans first began bathing in in Japan is unknown, but historical records show it has a history of at least about 1,300 years. Many of the earliest records of bathing document Japanese Emperors or members of the imperial family staying at for long periods of time. At the time, were thought to be sacred and to have healing properties. It is now believed those who traveled to in these early records were seeking cures to disease or other ailments by bathing in the water. This ancient practice of bathing in to cure illnesses, often for long periods such as a week, is referred to as tà Âji (). Some of the oldest in Japan are considered to be Dogo Onsen in Ehime Prefecture, Shirahama Onsen in Wakayama Prefecture, and Arima Onsen in Hyogo Prefecture.
Until around the Edo period, had close religious ties to Buddhism with temples often being built near sources. During the Edo period, however, began to gain popularity among the general population thanks in part to depictions of the hot springs in ukiyo-e. It is also during this period that the use of shifted from being primarily for religious and healing reasons to being used for bathing for cleanliness and socializing.
In modern times, traveling to is a popular form of domestic tourism in Japan. During the bubble economy of the 1980s, there was a " boom." Although the number of overnight guests at hot spring resorts has decreased slightly since the boom, travel to such towns as a relaxing getaway is still popular among Japanese people.
Traditionally, men and women bathed together at both and sentà  communal bathhouses, but gender separation has been enforced at most institutions since the opening of Japan to the West during the Meiji Restoration.
is currently banned in Japanese public baths. Depending on the prefecture and local ordinances, children seven years old and younger may be exempt from this ban.
Private called can be found in many locations throughout Japan. These can be reserved and used for mixed bathing.
In the Japanese language, means Woman and means Man. The characters and (pronounced yu) stands for Hot water, but also for a Bathing or . Generally, there is a separation called curtains.
Onsen are a location where considerable offense can be caused if the proper social etiquette is not observed. The general procedure and expected etiquette closely resemble those used at a sento certain hours where outsiders may purchase day passes to enter. Standalone onsen open to the public also exist. Onsen are considered more of a special experience than the sento, which is used for common bathing. Due to their integrated location within a hotel, an entry attendant is rare and bathers will usually wear the hotel-provided yukata and indoor slippers to walk from their rooms to the onsen. Towels are provided to guests at the entry, and shower stations and vanities are fully stocked with toiletries and conveniences for bather's use, instead of guests being required to bring their own or purchase such items separately. Guests should not take wet towels or toiletries back with them or hoard the complimentary items. While it is common after a bath in the sento to quickly re-shower before leaving, many onsen bathers skip this second shower to keep the minerals from the hot spring on their skin. Onsen within ryokan or hotels are generally kept open 24 hrs a day, or only closed for a brief daily cleaning period, to allow guests to freely bathe in the middle of the night if the whim takes them. Popular, private, or specialized baths may require reservations or additional fees.
As at a sentà Â, at an , all guests are expected to wash and rinse themselves thoroughly before entering the hot water. Bathing stations are equipped with stools, faucets, rinsing basins, and complimentary toiletries such as soap and shampoo; nearly all onsen also provide removable shower heads for rinsing convenience. Entering the while still dirty or with traces of soap on the body is socially unacceptable.
One's hair should never touch the bath water and should be worn up.
Even though onsen can be a luxury experience and environment, guests are still expected to clean up after themselves by staying tidy and rinsing off their shower area for the next guest.
Guests are not allowed to wear swimsuits in the baths or showers and must be completely nude.
The only time swimsuits are allowed and required are in specific modern pools which allow both men and women to use them together, but many of these mixed resemble more of a pool or waterpark than the traditional idea of an .
guests generally have a small towel with them to use as a drying cloth, since re-entering the changing area while dripping wet is a faux-pas. The towel can also provide a modicum of modesty when walking between the washing area and the baths by holding it loosely in front of your genitals. Though many TV shows depict characters wearing a towel in the bath, this is a television invention used for actor modesty and wearing towels into the bath is forbidden. It is against the rules to immerse or dip towels in the bath water, since this is considered unclean. People normally set their towels off to the side of the water when enjoying the baths, or place their folded towels on top of their heads to keep them out of the water.
By 2015, around half (56%) of operators had banned bathers with tattoos from using their facilities. The original reason for the tattoo ban was to keep out yakuza and members of other crime gangs who traditionally have elaborate full-body decoration. In 2016, the Japan Tourism Agency urged operators to allow foreign customers with tattoos to use the on a conditional basis in order to accommodate the increasing number of foreign tourists. On the other hand, operators wanted foreign customers to enjoy the , but were concerned that allowing foreign customers with tattoos to use the would prevent them from keeping yakuza out of the .
However, tattoo-friendly do exist. A 2015 study by the Japan National Tourism Organisation found that more than 30% of operators at hotels and inns across the country will not turn someone with a tattoo away; another 13% said they would grant access to a tattooed guest under certain conditions, such as having the tattoo covered up. Some towns have many tattoo-friendly that do not require guests to cover them up. Two such towns are Kinosaki Onsen in Hyà Âgo and Beppu Onsen in à Âita.
With the increase in foreign customers due to growing tourism, some that previously banned tattoos are loosening their rules to allow guests with small tattoos to enter, provided they cover their tattoos with a patch or sticking plaster.
There are various health benefits attributed to bathing in . are particularly renowned for their relaxing and therapeutic effects. These effects are due to properties such as the temperature, pressure, and mineral composition of the water.
A 2014 study conducted in Beppu, a city famous for its , found that regular bathing in has various health benefits such as lowering blood pressure, improving circulation and cardiovascular health, reducing chronic pain and fatigue, and lowering the rate of depression. A survey conducted in Atami, another city famous for its , found that individuals with in their homes were less likely to take blood pressure medication than those without .
There are various types of including carbonated springs, iron-containing springs, acidic springs, strong-smelling sulfur springs, among others. Each type of is believed to have unique benefits. Carbonated springs, for example, are believed to lead to smooth skin. facilities often advertise various health and beauty benefits they claim their water to provide.
Water at some facilities is drinkable. water should only be consumed if it is confirmed to be safe to drink by the prefecture. The water should be obtained from a designated drinking source that is separate from the water which is bathed in. The often mineral-rich water is believed to have benefits such as treating iron-deficiency anemia or constipation.
Article 18, paragraph 1 of the Japanese Hot Springs Act publishes guidance on contraindications and cautions for bathing in hot springs, and drinking their respective waters. Although millions of Japanese bathe in every year with few noticeable side effects, there are still potential side effects to usage, such as aggravating high blood pressure or heart disease.
Legionella bacteria have been found in some with poor sanitation. For example, 295 people were infected with Legionella and seven died at an in Miyazaki Prefecture in 2002. Revelations of poor sanitary practices at some have led to improved regulation by hot-spring communities to maintain their reputation.
There have been reports of infectious disease found in hot bodies of water worldwide, such as various Naegleria species. While studies have found the presence of Naegleria in hot spring waters, Naegleria fowleri, responsible for numerous fatal cases of primary amoebic meningoencephalitis around the world, has not been found to be present in the water at . Nevertheless, fewer than five cases have been seen historically in Japan, although not conclusively linked to exposure.
Many display notices reminding anyone with open cuts, sores, or lesions not to bathe. Additionally, in recent years onsen have been increasingly adding chlorine to their waters to prevent infection, although many purists seek natural, unchlorinated that do not recycle their water but instead clean the baths daily. These precautions as well as proper usage (i.e. not placing the head underwater, washing thoroughly before entering the bath) greatly reduce any overall risk to bathers.
Voyeurism is reported at some . In 2016, The Japan Times reported that this was mitigated in some prefectures of Japan where nude mixed bathing is not permitted, and that visitors must wear swimsuits. In 2021, several people were arrested in connection with an organized group accused of taking photos of women in open-air baths.
In addition to typical and , there are various other methods of experiencing that can be found at various facilities throughout Japan. Examples include:
Saunas are also sometimes located at bathing facilities. A relatively cold bath called is often located directly outside a facility's sauna to allow users to quickly cool down. The cycle of entering hot baths, saunas, and cold baths at an facility is sometimes referred to as and is believed to be refreshing and to have health benefits.