The sequence
Shoes off at the entrance. Pay, take the small towel, and go through the curtain marked for your gender — red or a female character for women, blue or a male character for men. The curtains sometimes swap sides on alternate days, so read rather than assume.
Undress completely in the changing room and put everything in a basket or locker. No swimwear. Take only the small towel through to the bathing room.
Wash first, sitting on a low stool at the taps. Soap, rinse, rinse again. This is not a formality — the bath is for soaking in, and everyone in it has done this.
Then get in slowly. Onsen water often runs 41–43°C. Fold the small towel and rest it on your head or the rock beside you; it does not go in the water.
The four rules that matter
- Wash thoroughly before entering. Everything else is negotiable; this is not.
- No towel, hair or swimwear in the water. Tie long hair up.
- No swimming, splashing, diving or noise. It is a quiet room.
- Do not put soap in the bath, and do not rinse off in it.
Tattoos
Historically barred, on the basis of an association with organised crime, and still barred at some establishments. Enforcement varies enormously — many places have relaxed, particularly in areas used to foreign visitors, and many have not.
The workable answers: look for tattoo-friendly listings, use a private family bath (kashikiri, bookable by the hour), stay at a ryokan with an in-room bath, or use cover-up patches for something small. Asking at the desk is fine and the answer will be straightforward.
Where to do it properly
- Kinosaki Onsen, Hyogo — seven public bathhouses in one small town, walked between in yukata and wooden geta.
- Kurokawa Onsen, Kumamoto — a wooden village in a gorge, with a pass covering three outdoor baths of your choosing.
- Nyuto Onsen, Akita — remote, milky sulphur water, and Tsurunoyu's 350-year-old inn under snow.
- Any neighbourhood sento — a few hundred yen, no ceremony, and the version locals actually use.
The anxiety is almost entirely anticipatory. Nobody is looking at you, and the water is very good.