1. Types of venue
| Term | Reading | Meaning |
|---|---|---|
| 旅館 | ryokan | Inn with tatami rooms and meals |
| 湯治場 | tōjiba | Cure-bath town for long therapeutic stays; often has self-catering wings |
| 共同浴場 | kyōdō yokujō | Locally run communal bath; roughly the same as sotoyu |
| 外湯 | sotoyu | Public bath in an onsen town, as opposed to an inn's own 'uchiyu' |
| 日帰り温泉 | higaeri onsen | Day-use bathing facility, no lodging |
| 立ち寄り湯 | tachiyori-yu | Drop-in bathing offered by an inn to non-guests |
| スーパー銭湯 | sūpā sentō | Large urban bath complex; not necessarily a hot spring |
| 秘湯 | hitō | 'Hidden spring' — a lone inn deep in the mountains |
| 足湯 | ashiyu | Free foot bath |
| 砂湯・蒸し湯 | sunayu / mushiyu | Sand bath (Ibusuki), steam bath (Beppu) |
2. Reading water quality
| Term | Meaning |
|---|---|
| 源泉かけ流し gensen kakenagashi | Source water flows through once, with no dilution, heating or recirculation. The gold standard |
| 加水 kasui | Water added to cool the source. Necessary where it's too hot |
| 加温 kaon | Boiler-heated. Necessary where the source is lukewarm |
| 循環（ろ過） junkan | Filtered and recirculated; usually chlorinated |
| 消毒 shōdoku | Disinfection (chlorine etc.); legally required for recirculated water |
| 湧出量 yūshutsuryō | Litres per minute. More means fresher |
| 泉温 sen'on | Source temperature. Legally 'onsen' if ≥25°C or meets mineral thresholds |
| pH | ≤2 strongly acidic (Kusatsu, Tamagawa); ≥8.5 alkaline ('beauty baths') |
| にごり湯 nigoriyu | Cloudy water — white, brown, green. Typical of sulfur and iron springs |
| 湯の花 yunohana | Mineral flakes floating in the water. Not dirt |
| 泉質名 | Spring types: simple / chloride / bicarbonate / sulfate / sulfur / acidic / iron / carbon-dioxide / radioactive / iodine |
| 適応症・禁忌症 | Conditions it's said to help / conditions that rule out bathing |
| 美肌の湯 bihada-no-yu | 'Beautiful-skin water' — usually bicarbonate, alkaline simple or sulfate springs |
| 温泉分析書 | Analysis chart, legally displayed in the changing room; lists everything above |
3. Words you'll see in the bath area
| Term | Meaning |
|---|---|
| 男湯・女湯 | Men's (男 / 殿, blue curtain) and women's (女 / 姫, red curtain). Watch for daily swaps |
| 脱衣所 datsuijo | Changing room |
| 洗い場 araiba | Seated washing area; karan = tap |
| かけ湯 kakeyu | Rinsing yourself before entering |
| 内湯・露天風呂・野天風呂 | Indoor / open-air / fully exposed outdoor bath |
| 貸切風呂・家族風呂 | Private bath reserved for one party |
| 客室露天 | Open-air bath attached to a guest room |
| 湯浴み着 yuamigi | Bathing wear for mixed baths |
| 混浴 kon'yoku | Mixed-sex bath |
| 打たせ湯 utaseyu | Water falling from above onto the shoulders |
| 寝湯 neyu | Shallow bath for lying down |
| 壺湯 tsuboyu | Single-person ceramic tub |
| サウナ・水風呂・外気浴 | Sauna, cold plunge, outdoor rest — the 'totonou' trio |
| 岩盤浴 ganban'yoku | Lying on heated stone slabs, clothed |
| 清掃中・入替中 | Cleaning / changeover — closed |
| 女性専用時間 | Women-only hours in a mixed bath |
4. Fees and procedures
| Term | Meaning |
|---|---|
| 入浴料 nyūyokuryō | Admission: adult / child (primary school) / infant |
| 入湯税 nyūtōzei | Bathing tax, about ¥150 per person per night, added to lodging bills |
| タオルセット | Face towel plus bath towel, rented or sold |
| 手ぶらセット | 'Empty-handed set' — admission with towels and amenities |
| 湯めぐり手形 yumeguri tegata | Pass valid at several baths or inns |
| 回数券 kaisūken | Book of 10–11 discounted tickets |
| 券売機 | Ticket vending machine; ¥1,000 notes and coins |
| 受付 uketsuke | Reception (also 'bandai'); you get a key and return it on leaving |
| 下足箱 gesokubako | Lockable shoe box, often ¥100 refundable |
| 一泊二食 ippaku nishoku | One night with dinner and breakfast |
| 素泊まり sudomari | Room only, no meals |
| チェックイン15:00・アウト10:00 | Standard ryokan times |
| 日帰りプラン | Day plan: lunch, bath and room rest |
| 定休日 teikyūbi | Regular closing day; 不定休 = irregular |
| 臨時休業 rinji kyūgyō | Unscheduled closure — phone ahead |