Onsen (温泉) in Japanese means “hot source.” The hot comes from the volcanoes across the country. Volcanoes generate geothermic energy which heats natural springs.

The Japanese have flocked to hot spring baths for more than a thousand years. Today, onsen attract visitors from all over the world.

wooden onsen pass
Wooden onsen pass. Photo credit: Karen Kao

When my husband and I visited Japan in 2015, we spent a few idyllic days at an onsen resort in Kyushu prefecture. We bought a rotemburo meguri so we could visit three different onsen in addition to our own. Clad only in thin cotton yukata with our tegata (wooden pass) around our necks, we clattered around Kurokawa on our geta to try the various baths.

This was a tourist experience we had to repeat during our round-the-world adventure.

A public bath

In Japan, onsen are regulated under the Onsen Ho or Hot Springs Act. The water source must be a hot spring with a minimum temperature of 25℃, heated at the source with a specific mineral content.

By contrast, a sento (銭湯) or “coin hot water” is a public bath filled by heated tap water. You can still find them in the big cities dating back to when Japanese homes did not have indoor bathrooms.

There are many uses in Japan for hot water, including boiling your enemies.

At sunset Omi watched Zukimoto, puffed with vanity, supervising while the barbarian was trussed like a chicken, his arms around his knees, his hands loosely to his feet, and put into cold water. […] Then the stoking of the fire began.

James Clavell, Shogun (Dell 1975)

The barbarian here is a sailor shipwrecked off the coast of Japan. The locals boil him alive in the cauldron they normally use to render whale blubber.

When the Tokugawa shogunate expelled the Portuguese and Spanish missionaries in 1614, they boiled, burned and hung the Japanese converts.

Mixed use onsen

Map Tsurunoyu Onsen
Map of Tsurunoyu Onsen

Today, an onsen is more than a natural pool of hot spring water. Our inn at Tsurunoyu Onsen boasts traditional tatami matted rooms and three exquisite meals a day. Between meals, we spend our time trying out the many pools ⏤ indoor and outdoor, single sex and mixed.

Our onsen did not offer services like hairdressing or massage. Nor did I see any bath maids. Maybe they were in the men’s bath.

The mama-san […] sent Noriko off to a toruko where she would have to bathe and serve men in the nude until she was too old to work that job. Her tits and ass would last half a dozen years at most in the hot water. Then she would have to find something else to do.

Min Jin Lee, Pachinko (Grand Central Publishing 2017)

The association between onsen and prostitution is almost as old as the onsen themselves. In the city, a geisha is an “art person”, not a prostitute for hire. An onsen geisha is a social outcast.

The hot-spring inn had its fewest guests in the weeks before the skiing season began, and by the time Shimamura had come up from the bath the place seemed to be asleep. The glass doors rattled slightly each time he took a step down the sagging corridor. At the end, where it turned past the office, he saw the tall figure of the woman, her skirts trailing coldly off across the dark floor.
He started back as he saw the long skirts ⏤ had she finally become a geisha?

Yasunari Kawabata, Snow Country (Alfred A. Knopf 1957), translated by Edward G. Seidensticker

In snow country

Tsurunoyu Onsen lies in northern Japan, snow country. The onsen has been in operation since the 17th century when a hunter saw a crane heal its wounds in the spring. The Japanese have long believed in the healing properties of an onsen. There is now scientific research conducted by Shinya Hayasaka, a medical doctor and professor at Tokyo City University, to bolster the claim.

“There are three main health benefits of bathing regularly: heat, buoyancy and hydrostatic pressure,” said Hayasaka. “Good personal hygiene and cleanliness are also beneficial for health, of course, but this can be obtained just as well by taking a shower. For the other three, though, you need to immerse yourself in hot water.”

Julian Ryall, “Japan’s ‘onsen’: A hot bath every day keeps doctors away” in Deutsche Welle, 25 Dec 2020
bears in onsen
Bears in an onsen. Photo credit: Karen Kao

Heat causes the arteries to expand, allowing oxygen and nutrients to travel move freely through the body while removing waster. When the body is buoyant, the muscles can relax. The hydrostatic pressure functions as a massage for the lower body and legs. Daily onsen bathing is particularly beneficial for old folks like me by reducing the risk of stroke and increasing longevity.

Snow falls on our last day at Tsurunoyo Onsen. After three days of bathing, I smell like rotten eggs. At least now I know how to use an onsen.

Outdoor slippers off and stored in the wooden rack as you come in the door. Undress (a simple task since all I’m wearing is my sleeping yukata and the outdoor jacket) and place my clothes into one of the wicker baskets waiting on the shelf. Wash myself using the hand shower and, as needed, soap, shampoo and conditioner. Acclimate my body to the 60 degree bath temperature indoors or the 45 degrees outdoors by filling a plastic bucket with bath water and throwing it onto me. Position my modesty towel, folded, on top of my head. Sink into the heat.

Karen Kao, Travel journal entry for 13 Nov 2019