A guide to the tags used in the database so you can filter for the bathing experience you want.
Public
This facility is open to the public. Public facilities are run by a private business. They're often no-fee or very inexpensive (i.e. 100 JPY) and payment is on an honor system, usually a collection box at the entrance.
No Fee
This facility is free to use. No payment is required for entry or usage.
Ryokan
This onsen or bath is located inside a ryokan, a traditional Japanese inn. Unless this facility also has the Day Use tag, you must stay overnight at the ryokan to use it.
Hotel
This onsen or bath is located inside a hotel. Unless this facility also has the Day Use tag, you must stay overnight at the hotel to use it.
Day Use
This facility can be used on a day-use basis, without staying overnight. Unless this facility also has a Ryokan or Hotel tag, this facility is not usable at night.
Mountain Hut
This facility is located in a mountain hut, typically found in alpine or forested areas. These facilities are often seasonal and may be accessible only during specific times of the year. For some mountain huts, the only way to access them is to hike or trek, often for several hours. The notes will have a comment about accessibility.
Private Bath
This facility has private baths available, either as part of an overnight stay booking or available as a separate service. Some day-use facilities also offer private baths. (If so, they'll be tagged as such.) Almost always, private baths can be shared by multiple people in a party, and mixed bathing is allowed.
Sauna
This facility has a sauna. In Japan, saunas are often dry, but not always. Facilities with a sauna often also have a Cold Plunge.
Cold Plunge
Cold bath, or 水風呂 / みずぶろ / "water bath." This facility has a bath filled with very cold water.
Indoor Bath
The bathing area is located indoors, typically within a building or structure. This is the most common configuration, but some facilities are outdoor-only!
Outdoor Bath
The bathing area is located outdoors, typically in a natural setting such as a garden or open-air area, although even facilities in the city sometimes have outdoor baths.
Mixed Bathing
This facility allows both men and women to bathe together in the same area. Most facilities are gender-separated, but some do allow mixed bathing, either always, on certain days or during certain times. Policies about body covering during mixed bathing vary by facility. Some facilities require men to cover themselves with a towel or loincloth while bathing. Others prohibit men from covering themselves during mixed bathing. Often, women have the option to cover or not with a special "bathing dress" or towel provided by the facility.
Onsen
This facility is a traditional Japanese hot spring bath, often found in rural areas or smaller towns.
Sento
This facility is a traditional Japanese public bathhouse, often found in urban areas. Sento facilities are typically community-oriented and may have a more casual atmosphere compared to private or high-end establishments. I've never been to a sento that cared about tattoos, so these are overwhelming safe places for tattooed people!
Super Sento
A modernized version of a traditional Japanese public bathhouse, often larger and featuring upgraded amenities and facilities compared to regular sento. Super sento often have some kind of restaurant or food service, large areas for relaxation and socializing, and may offer additional services, such as massage therapy.
Foot Bath
This facility is a foot bath, typically located outdoors, no-fee, and open to the public. You can sit on the edge and soak your feet in hot sprint waters.
Adjustable Temp
The temperature of the bath can be adjusted by the user. This is typically only found at very rustic locations, basic public facilities, or private baths that you must reserve with or without an overnight booking.
Cold Spigot
This facility is equipped with a cold water tap. This can be used in place of a cold plunge if you're into that!
Electric Bath
電気風呂, or でんきぶろ, or denkiburo. This facility has a bath with an electrical current running through it that provides an electro-stimulating effect in your body when you enter the bath. Sometimes this effect can be very intense, so be careful! You can tell when a bath is electrified from the signage (look for the 電 kanji on the wall) or, when you look into the bath, you'll see two panels on the walls of the bath, one each on opposite sides. These panels carry the current into the bath water.
