Bathing in an onsen is probably the most iconic Japanese experience, and the one that creates the most anxiety for foreign travelers. Do you have to get completely undressed? What about the little towel? And tattoos? Don’t panic. The rules are simple, and Japanese people are forgiving with anyone making the effort. This guide covers the onsen and the sento, the step-by-step ritual, the classic pitfalls, and all the questions nobody dares ask out loud.
Onsen or Sento, What’s the Difference?
The two words are often confused, but they describe different things.
An onsen (温泉) is a hot-spring bath, fed by a real geothermal source. Japan’s 1948 Hot Springs Law defines it strictly: minimum 25°C at the source, or a specific mineral composition. It’s the water that makes the onsen, not the building.
A sento (銭湯) is a neighborhood public bath, with no natural source. The water is simply heated from the tap. Historically it was the everyday bath, back when most Japanese homes didn’t have a bathroom. Sento are rarer today, but the survivors are often beautiful: 1950s architecture, painted Mount Fuji murals, high ceilings, an out-of-time atmosphere.
In practice, the ritual is exactly the same in both. And a neighborhood sento at ¥500 is often a more authentic experience than a tourist onsen at ¥3,000. In Tokyo, sento like Takara-yu in Adachi are well worth the detour.
The Ritual, Step by Step
The ritual is invariant, whether you’re in a Tokyo sento or a grand Hakone onsen. Follow these steps and you’ll do fine.
- At the entrance. Take off your shoes, put them in a shoe locker, pay at the counter (typically ¥300 to ¥1,000).
- Changing room. Strictly separated by gender (blue curtain for men, red for women, but it’s not universal, look for the characters 男 and 女). Get fully undressed, fold your clothes into a locker.
- The small towel (tenugui). Take it with you. That’s all you bring into the bathing area. If the establishment provides it, it’s in the locker.
- In the bathing room. Sit on a small plastic stool in front of a tap, grab the handheld shower, wash yourself completely, soap and shampoo. This step is non-negotiable: you always enter the bath clean.
- The bath. Enter slowly (water is usually 40 to 44°C, 104 to 111°F). Stay 5 to 15 minutes, get out if you’re too hot, cool off, come back.
- Getting out. Optional final rinse, back to the changing room, towel dry, get dressed.
The Essential Rules
1. Wash before entering the bath. This is THE rule. The pool water is shared by everyone. You never wash in it. Soap, shampoo, full rinse on the stool. Only then do you enter.
2. No swimsuits. Traditional onsen and sento are done nude. It’s disconcerting at first, but everyone is in the same boat. No one looks, no one judges.
3. The towel never touches the bath water. Place it on your head (the classic move), or leave it on the edge of the pool. Never in the water, never wrung out into the water.
4. Tie up long hair. It must not soak. A hair tie or clip is enough.
5. Stay silent or speak quietly. The onsen is a contemplative space. No phones, no photos, no music. Enjoy the calm.
6. No alcohol in the bath. And ideally none before either. Heat plus alcohol causes lightheadedness. Save the sake for afterwards, in yukata.
The Tattoo Question
This is the most-asked question, and the answer has evolved in recent years. Historically, onsen and sento banned tattoos because of their association with yakuza (Japanese mafia). The rule has been softening since 2020, partly under pressure from international tourism.
Your options today:
- Tattoo-friendly onsen. Increasingly common. Kinosaki is openly welcoming, many establishments in Kyushu as well. JNTO maintains an up-to-date list.
- Cover-up patches. For small tattoos (under 10 cm), skin-tone stickers cover them discreetly. Many establishments accept this.
- Kashikiri (貸切, private bath). Most ryokan offer them, bookable for 30 to 60 minutes (¥1,500 to ¥5,000). Ideal for couples, families, or tattooed travelers.
- Ryokan with an in-room bath. The luxury version. Expect ¥30,000 to ¥80,000 per night, but the experience is unmatched. See The Best Ryokan in Japan for selections.
When in doubt, ask before arriving. The phrase to learn: Tatū wa daijōbu desu ka? (Are tattoos OK?). A simple email to the ryokan usually settles it.
Practical Tips
Stay hydrated. Drink water before and after. Most changing rooms have fountains or vending machines.
The water is hot. Really hot. Some baths exceed 43°C (109°F). Enter gradually, and if you feel dizzy, get out and take a break on the stool. Alternating between hot bath and cool air (or a cold bath if available) is part of the experience.
Bring two towels (unless the establishment provides them, common in ryokan). A small one to cover yourself walking and to place on your head in the bath, a large one to dry off afterwards.
Bring cash. Small neighborhood onsen and sento often only take cash. Entry is typically ¥300 to ¥1,000.
No jewelry. Acidic or sulfurous waters can tarnish silver and certain metals. Leave rings, necklaces, and watches in the locker.
FAQ: The Questions Nobody Asks Out Loud
Do I have to shave first? No. No obligation, no expectation. It’s a foreign-traveler myth. Nobody looks.
What if I’m on my period? Traditional usage is not to bathe. A discrete tampon can work, but it’s a judgment call. No onsen checks. It’s about respect for the collective.
How long should I stay? 5 to 15 minutes per session, then out, rest, back in if you want. The sense of well-being builds across multiple entries, not from sitting 30 minutes straight.
Can I drink water in the bath? A water bottle at the edge of the pool is accepted and even recommended by Japanese bathers themselves. Dehydration is the number-one risk in a hot bath.
Mixed-gender onsen (konyoku)? Very rare today (fewer than a hundred in Japan). Some accept a light wrap for women. If you go to one, signage is usually clear.
Onsen with kids? Welcome, but subject to the same rules (especially washing first). Babies and young children are generally allowed in the women’s section until age 6 or 7, then they cross to their gender section.
What if heat makes me claustrophobic? Prefer rotenburo (露天風呂), the outdoor baths where air circulates. Much more tolerable than enclosed indoor pools.
Which onsen should I pick for my first time? A neighborhood sento (intimidating for the nudity but authentic and cheap), or an accessible onsen like Hakone. For a real destinations selection, see The Best Onsen in Japan.
Going Further
Etiquette is half the experience. The other half is picking the right onsen. For the top 10 destinations worth one or three nights, see The Best Onsen in Japan. For the full experience (with kaiseki dinner, yukata, futon), see The Best Ryokan in Japan.
The onsen looks complicated from the outside and becomes natural by the second time. Follow the six rules, stay quiet, and enjoy. After your first bath, you’ll understand why Japanese people see it as an art of living. And you’ll probably want to go back the next day.