The Rules of the Bath

I grew up around onsen in Kyoto, and I still got it wrong the first time I went on my own. I rinsed at the shower for about ten seconds, climbed in, and an older woman across the bath gave me a look that needed no translation. I got out, washed properly, and came back. Nobody said anything. They didn't need to.

That's the thing about onsen etiquette. It sounds like a list of prohibitions written to keep outsiders out, and it isn't. Every rule comes from one idea: the bath is for soaking, not cleaning, and everyone shares the same water. Once that lands, the rest follows on its own. The nudity, which is the part everyone worries about, turns out to be the part that matters least.

This is the public side of the bath, day-use onsen and the neighbourhood sentō. If you're after the in-room version, the bath as part of a ryokan stay, that's its own ritual and I've written about it elsewhere. Here I want the communal water.

Onsen or Sentō

The words get used loosely, so it's worth a line. An onsen runs on natural hot-spring water. Under Japan's Hot Springs Act it has to come up warm enough at the source - at least 25 degrees - or carry enough dissolved minerals, to count.^[1] A sentō is a neighbourhood bathhouse heated from the tap. Same etiquette in both, different water and different mood. The onsen is somewhere you travel to. The sentō is the bath at the end of your street, and the fare is capped by the prefecture: in Tokyo it's ¥550 for an adult, fixed by the metropolitan government.^[2]

For etiquette, the distinction barely matters. What follows works in both.

What Actually Happens

Here's the sequence, start to finish. You arrive and your shoes come off at the entrance, into a locker or a shoe shelf. At the desk you pay, or show your room key if you're staying somewhere with a bath. Then you find the right curtain. Men's baths hang a noren marked 男（おとこ）, women's one marked 女（おんな）, and the colours usually follow - blue or dark for men, red for women. Kanji defeating you? Go by the colour.

Through the curtain is the changing room, the datsuijo: lockers down one wall, wicker baskets stacked along the other. You undress completely. There's no swimwear in an onsen, none, and you leave your big towel and your clothes in the basket. The only thing that comes with you into the bathing area is the small towel.

Now the part everything else hangs on. Before you get anywhere near the bath, you sit down at a washing station, a row of low stools facing showerheads, soap and shampoo already there, and you wash. Properly. Hair, body, the lot, then rinse it all off. This is not a courtesy rinse before the real bath. This is the real cleaning, and the soak afterwards is the reward. People notice if you skip it. What do they notice? The water clouds, and everyone knows why. I noticed, the day I got the look.

When you're clean, scoop a little of the hot water over yourself before you climb in. That's kakeyu. It rinses off the last of the soap and lets your body meet the temperature before the rest of you commits. Then lower yourself in by degrees. Most onsen water sits somewhere around 40 to 44, well past the temperature of a bath you'd run at home, and dropping in all at once is how you end up gasping.

Then you soak. That's the whole instruction. No timer, no technique. Some people shut their eyes, some talk quietly, some just watch the steam. Stay until you're warm, get out, cool off on the side, go back in if you fancy it. Nobody's counting.

The Towel and the Heat

Two practical things trip people up, so I'll be blunt about both.

The towel rule is absolute and it's the one visitors break most. The small towel does not touch the bathwater. Fold it on your head, set it on the rim, leave it on your shoulder. Anywhere but in. It carries soap and whatever you've just scrubbed off, and the water is shared. That's the entire reason. There's no superstition to it.

The heat is the other one. At 42 or 43 degrees you can overheat faster than you'd think, especially if you've just stepped off a train and you're dehydrated. Yuatari is the word for the dizziness that follows. Drink water before and after. Most facilities have a rest area with cold water or a vending machine, and the bottle of coffee milk after a long soak is a tradition I'll defend to anyone. Don't submerge your head. Don't go in drunk. If you start feeling light, get out and sit down; it passes.

The Tattoo Question

This is the one that genuinely worries people, and the honest answer is that it depends on where you go.

Plenty of onsen still turn away tattooed bathers, a rule that traces back to the association between tattoos and organised crime. It's a house policy, not a law, and it's been loosening - slowly, and unevenly. The clearest number we have is dated: a 2016 Japan Tourism Agency survey found that of the facilities that responded, 56 per cent refused guests with tattoos, 31 per cent allowed them, and 13 per cent admitted them on condition the tattoo was covered.^[3] The agency has been pushing facilities to relax since. More recent figures float around, but they vary by who's counting, so I'd treat the 2016 split as the firm ground and everything after it as drift in the right direction.

If you have a tattoo, you have options. Phone ahead and ask: the single most useful thing you can do, and staff are used to the question. Carry skin-coloured cover patches for anything small; convenience stores and pharmacies sell them, and some baths keep them at the desk. Seek out places that advertise themselves as tattoo-friendly. Beppu, which I keep going back to, leans that way across a lot of its baths, though I'd still check the specific one before I went.

The Naked Part

Which brings us to what people actually lose sleep over. How do you stand there, undressed, in front of strangers?

I understand the worry. Undressing completely in a room full of strangers runs against everything most of us are trained into. And then you do it, and within a minute or two it's gone. I'm not exaggerating for reassurance. It really is that fast.

Here's why. Nobody looks at you. Partly that's manners, but mostly it's that everyone is in exactly the same state and occupied with their own soak. The room is steamy and half-blind. There are no clothes, so there are no labels. You can't tell the company director from the man who fixes bicycles, and after a few minutes you stop trying. The body is just a body. That levelling is the quiet thing onsen do that the temperature gets all the credit for.

If the communal version still feels like a lot, start with a private bath and work up to it, or go at a dead hour, mid-afternoon on a weekday or late at night, when the room is nearly empty. Watch the person ahead of you; the sequence is the same everywhere and following someone who clearly knows it is no shame. Take your extra moment at the shower. The staff have seen every possible mistake, the other bathers have their eyes shut, and the water has no opinion about how you look.

I have a few baths I return to, one in Beppu in particular, and it isn't only that the water's good. Some baths hold every previous visit you've made. You lower yourself in, the heat does its old trick, and for a moment the years fold together. That's the part no guide can hand you, and it's the reason I keep getting back on the train.