Ganban'yoku

Ganban'yoku (岩盤浴) is a Japanese bathing method in which an individual lies on heated natural stones in a humid room which itself is usually heated to between 40-50°C (104-122°F).^[1] The use of ganban'yoku is believed to have positive effects on both health and beauty.^[2]

Tamagawa Onsen in Akita Prefecture is said to be the birthplace of ganban'yoku bathing in Japan.^[3] At Tamagawa Onsen, visitors can lie on exposed geothermally heated hokutolite stones.^[3] The first specialized ganban'yoku facility opened in Kesennuma, Miyagi Prefecture in 2001.^[3] From there, ganban'yoku facilities began opening throughout Japan in what has been referred to as a ganban'yoku "boom."^[3] Although the number of locations specializing only in ganban'yoku has decreased since the boom due to hygiene concerns, ganban'yoku rooms attached to onsen facilities can still be found throughout Japan.^[3]

Body-sized stones, such as germanium, are installed into the floor of a room which is usually heated to around 40-50°C (104-122°F).^[1] Bathers, usually dressed in kannaigi (館内着) which is a type of casual Japanese indoor wear similar to samue, place a bath towel on a stone and lie on it.^[2] The stones themselves are heated. The room's temperature, which is similar to that of a low-temperature sauna, combined with the heat of the stone cause users to sweat.

Like low-temperature saunas, ganban'yoku are commonly advertised to have a detoxification effect, improve the circulatory system, and be good for the skin.^[4] It is also considered to have a relaxing and stress-reducing effect.

Most modern ganban'yoku rooms are located at onsen facilities.^[3] As clothing is worn in the ganban'yoku rooms, they are separate from the nude bathing area and are mixed-gender. The onsen bathing area is usually visited after one uses a ganban'yoku in order to wash off the sweat caused by the warm room and stones.

• About ganban-yoku