Japan’s onsen (natural hot spring baths) and sento (public bathhouses) operate under a clear set of behavioral conventions that make communal bathing work smoothly for everyone. Getting these right is not difficult — the rules are logical once you understand their purpose — and observing them is the difference between a harmonious bath experience and an awkward one. This guide covers everything from the moment you enter a bathhouse to the moment you leave.
Before You Enter: Essential Basics
Tattoo Policy
Many traditional onsen and public baths prohibit tattoos — a policy stemming from historical associations with yakuza (organized crime). The prohibition is strict at conservative facilities; more progressive onsen and most urban sento are relaxing the rule. Always check before visiting. Options for tattooed visitors: private-room onsen (kashikiri rotenburo), onsen ryokan with in-room baths, or tattoo-friendly facilities (increasingly marketed as such). Some facilities offer covering patches or allow small tattoos covered with provided bandages.
Separate Bathing by Gender
Standard onsen and public baths have separate entrances and facilities for men (男, otoko, 男湯) and women (女, onna, 女湯). Mixed bathing (konyoku) is rare and clearly marked when available. Some facilities rotate baths between mornings and evenings for variety; check the schedule at check-in.
What to Bring
- Small towel: Provided by ryokan; bring your own to public baths (available to buy at the bath entrance for ¥100–¥200). Used for modesty when walking between areas — never placed in the bath water.
- Shampoo, conditioner, body soap: Many onsen provide these at the washing stations; check in advance or bring a small toiletry kit.
- Glasses and contact lenses: Remove contacts before entering mineral spring water (sulfur and acidic waters can cause irritation).
- No swimsuits: Communal onsen are entered naked. This is non-negotiable at traditional facilities.
The Bathing Process
Step 1: Change Room (脱衣所, Datsuijo)
Remove all clothing and store in a locker or basket. Leave your small towel — you can take it into the bathing area for modesty. Leave your phone in the locker; photography is absolutely prohibited in all bathing areas.
Step 2: Wash First (洗い場, Araiba)
This is the most important rule: wash your entire body thoroughly before entering the bath. Use the individual washing stations (low plastic stool, hand shower, soap, shampoo). Wash with soap and rinse completely. This is not optional or symbolic — the bath water is shared and unfiltered (at hot spring facilities). Entering the bath without washing is the most serious onsen etiquette violation.
Step 3: Enter the Bath
- Enter slowly — the water is hot (typically 40–44°C); sudden immersion can cause dizziness.
- Keep your small towel out of the water — fold it on top of your head or set it at the bath edge.
- Don’t splash, submerge your head, or make large movements disturbing other bathers.
- Speak quietly if at all; many onsen bathers prefer silence.
Bathing Duration
Typical bathing sessions are 10–20 minutes in the water; longer immersion in very hot water or strongly mineral springs can cause heat exhaustion. Kusatsu’s traditional jikan-yu (timed bathing) limits immersion to 3 minutes. Exit the bath if you feel dizzy or overheated. Rest on the bathing area benches or in the changing room between soaks — bathing in multiple sessions (in and out several times) is common and encouraged.
After Bathing
- Rinse your body briefly before leaving the bathing area.
- Towel dry as much as possible before entering the change room — dripping water on the change room floor is inconsiderate.
- Rehydrate — mineral hot spring water is dehydrating; drink water or sports drinks after bathing. Many facilities provide cold drinks near the exit.
- Rest for 20–30 minutes after bathing before vigorous activity.
Types of Onsen Water
- Sulfur (硫黄泉): The classic milky-white onsen; strong smell, skin-softening. Hakone, Beppu, Kusatsu.
- Sodium chloride (塩化物泉): Clear, salty water; excellent warming effect. Common coastal and lowland springs.
- Sodium bicarbonate (重曹泉): “Bijin no yu” (beauty water) — clear, alkaline; particularly soft on skin.
- Iron/acidic (含鉄泉/酸性泉): Rust-brown or colorless; Arima’s kinsen, Kusatsu. Stains towels.
- Carbon dioxide (炭酸泉): Mildly sparkling; stimulates circulation. Rare — Arima’s ginsen.