Onsen etiquette: the 12 rules to know before you get in

Two fabric curtains hang at the entrance of a Japanese public bath. One carries 男, the other 女. The colours, usually blue and red, are a habit rather than a rule: some establishments swap the curtains daily so that guests get to use both bathing halls in turn. The only reliable marker is therefore two characters, and it is the first thing a visitor should learn to read.

The onsen intimidates mainly because it works as shared infrastructure: everyone arrives clean, maintains the common water, and leaves without changing what the next bather will find. All twelve rules below follow from that single principle.

What the word onsen actually covers#

Japan's Hot Spring Act, passed in 1948, defines an onsen as groundwater meeting at least one criterion: emerging at 25 °C or above, or containing one of nineteen listed mineral components above a set threshold. A facility meeting neither is a sentō, a neighbourhood public bath heated from the mains, with the same customs but without the mineral claim.

The country counts on the order of twenty-seven thousand registered sources and close to three thousand hot spring resorts, according to the Environment Ministry's annual census. Some are ancient: Dōgo Onsen in Matsuyama is named in Japan's classical texts, Arima near Kobe appears in court chronicles, and Kusatsu in Gunma stands out for a natural flow rate among the highest in the archipelago.

One sign at the entrance deserves a visitor's attention: gensen kakenagashi means the source water flows through continuously without recycling, as opposed to a filtered and recirculated loop. That distinction, now a commercial argument, has a health basis: Legionella incidents in recirculating baths in the early 2000s led to tighter inspection.

Before you go in: four rules settled in the changing room#

Rule 1: read the characters, not the colours. 男 (otoko) marks the men's bath, 女 (onna) the women's. The curtain, or noren, may switch sides from one day to the next. If in doubt, the reception board and the changing room lockers repeat the information.

Rule 2: everything stays in the changing room. In the datsuijo you undress completely. Swimwear has no place in a classic onsen, except in the rare mixed complexes that explicitly require it. Clothes, watch and phone stay in the locker.

Rule 3: no photographs, ever. The changing room and the bathing hall are camera-free spaces without exception. This rule is not negotiable, and breaking it justifies immediate removal.

Rule 4: two towels, two purposes. You go in with a small towel, the tenugui, used for washing and for a rough dry. The large towel stays in the locker for afterwards. Long hair is tied up above the neck before entering.

In the bathing hall: four rules of sharing#

Rule 5: wash sitting down, before touching the pool. The araiba lines up shower heads at seated height, low stools and basins. You sit, soap up and rinse completely. The pool is for soaking in clean water, not for cleaning yourself.

Rule 6: rinse your station when you leave it. Before vacating the washing spot, rinse the stool, the basin and the surrounding tiles with clear water. The gesture takes five seconds and is noticed instantly when skipped.

Rule 7: the towel never touches the water. Fold it on the rim, or, in the classic move, put it on top of your head. Do not wring it over the pool and do not dip a corner to cool your neck.

Rule 8: the pool is a quiet place. Enter slowly, without diving or swimming. Do not float, scrub or comb your hair in it. Conversation is fine, at a measured volume: in a rotenburo, the outdoor bath, silence is as much part of the setting as the steam.

On the way out: four rules often missed#

Rule 9: do not automatically rinse off. Custom leaves the minerals to work on the skin after a soak. The nuance matters: for strongly acidic sources such as those in Kusatsu, or heavily sulphurous ones, a quick rinse is advisable, especially for sensitive skin.

Rule 10: dry off before the changing room. Wring yourself out with the small towel inside the bathing hall, before crossing the door. The changing room floor has to stay dry for those getting dressed.

Rule 11: drink water and do not overstay. Yuatari, the malaise of an overlong bath, shows up as dizziness. Ten to fifteen minute stints with breaks in between beat one continuous soak. Bathing after drinking alcohol is discouraged everywhere and forbidden in many establishments.

Rule 12: wear the yukata the right way round. The left panel folds over the right. The reverse is reserved for dressing the dead: it is the most visible and most avoidable mistake in a ryokan. The sash is tied simply, and the yukata is then worn throughout the building, corridors and dining room included.

The tattoo question#

Tattoos remain the main reason visitors are turned away. The origin is historical: body ink was long associated with Japanese criminal organisations, and many establishments adopted a blanket ban to reassure their regulars. A survey published in 2016 by the Japan Tourism Agency, covering several hundred hotels and inns, found that a majority refused tattooed guests, a minority accepted them without condition, and a further group admitted them provided the design was covered.

Four practical solutions exist. Adhesive cover patches sold in pharmacies, known as tattoo seals, cover small designs and satisfy the establishments that accept them. Lists of tattoo friendly facilities, maintained by regional tourism offices, have multiplied since the major international sporting events the country hosted. The kashikiri-buro, a bath privatised by the hour, sidesteps the issue and is booked at reception. Finally, some lodgings offer a private open-air bath attached to the room, the rotenburo-tsuki kyakushitsu, costlier but free of any restriction.

The bathing hall vocabulary#

Reading the water#

A board near the pool states the senshitsu, the official classification of the source. The Environment Ministry recognises ten families, among them simple, chloride, bicarbonate, sulphate, carbon dioxide, iron, sulphur, acidic, iodine and radon waters. The board also gives the temperature at emergence and, often, the uses traditionally associated with it.

These notices belong to an old spa culture, tōji, which meant staying several weeks in a resort for a course of treatment, with cheap lodging and self-catering. A few establishments in Tōhoku keep the formula alive, apart from the short-stay hotels.

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The Korean neighbour runs on the opposite logic: you stay dressed in provided clothing, and the bath becomes a social space for hours at a time.

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Same grammar of use: a handful of simple gestures, learned once, prevent every possible blunder.

The case of mixed bathing#

Konyoku, mixed bathing, was long the rural norm in Japan, until Meiji-era authorities, conscious of Western opinion, restricted it. It survives in a handful of mountain baths and riverside pools, often with recent adjustments: women-only time slots, separate entrances, or a provided bathing garment called yuami-gi. Local rules always take precedence over general custom, and they are posted.

A well kept onsen ends up resembling a warm library: everyone does the same thing, quietly, leaving the place exactly as they found it. A visitor who has grasped that principle no longer needs the list.

FAQ#

Do you have to be fully naked in an onsen? Yes, in a traditional bath separated by sex. Swimwear is only allowed in the rare mixed or water-park style facilities that explicitly require it. The small towel can shield you while walking around, but it must not go into the water.

Can you use an onsen with a tattoo? It depends on the establishment. A significant share of inns and hotels still refuses tattooed guests, according to the survey published in 2016 by the Japan Tourism Agency. The usual workarounds are a cover patch, finding a tattoo friendly facility, or booking a private bath.

Should you rinse off after bathing? Generally no, so the minerals keep working. Strongly acidic or sulphurous springs are the exception: a quick rinse protects sensitive skin. When in doubt, the notice beside the pool says so.

How long should you stay in the pool? Ten to fifteen minute stints, with seated breaks on the rim, suit most springs. Beyond that the risk of yuatari rises, especially in very hot water or after a meal with alcohol.

How do you wear a yukata correctly? The left panel goes over the right, never the reverse, which corresponds to dressing the deceased. The sash is tied at the side or in front, and the yukata is worn throughout the establishment, dinner included.

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