Ryokan Shirasagi

湯治のできる宿 しらさぎとうじのできるやど しらさぎ

Lodging
Kansai·Wakayama

Day Use

Yes

Bathing & Water

OnsenYes

Uses natural hot spring water

蓬来湯

Horai-yu

Operated by · (社)共済組合

Sampled at wellhead
Sulfur
Classification

Sodium Chloride-Carbonate spring

Horai-yu is a strongly alkaline simple sulfur spring (pH 10.1) — sharply slippery on the skin, sitting squarely in the Japanese 'beauty-water' family. At the wellhead the water carries a faint rotten-egg note of H₂S and a mild salty tang. Mineralization is light at 0.284 g/kg, so the character comes from the sulfur fraction (HS-, thiosulfate) and the high pH rather than from bulk solutes. Classified as a low-temperature spring (31.8 °C) heated for bathing.

pH
10.10
Alkaline
Source temperature
31.8°C
Low temp.
Tonicity
0.28g/kg
Hypotonic
Flow rate
146L/min
Typical
Color
colorless and clear
Taste
salty
Odor
faint hydrogen sulfide
Highlights
  • Sulfur-rich
  • Strongly alkaline

Analyzed Dec 18, 1997·和歌山県衛生公害研究センター·Cert no. 第6号-6

Programs

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SM
Sergey M
4 months ago

664. Ryokan Shirasagi, Tsubaki, Shirahama, Wakayama ★ Onsen with alkaline water (pH 10.1). Visited for higaeri for 600. Higaeri hours are 11:00-20:00 or 11:00-14:00 (varies by day). They stamp the Wakayama 88 Onsen book. They sell the Wakayama 12 Onsen stamp book. There is a gender rotation for baths. 1. First set of indoor baths by gender. A bit stuffy inside. View through old glass windows to the ocean. 1.1. Main bath with clear water, temperature around 41.5. 1.2. Coffee bath, temperature around 33. 1.3. Mandarin orange bath with clear water, temperature around 36. 1.4. Herbal bath (houttuynia). Clear water with a pale yellowish tint. Temperature around 35. 2. Second set of indoor baths by gender. A bit stuffy inside. View through old glass windows to the ocean. 2.1. Main bath with clear water, temperature around 43. 2.2. Yuzu bath with clear water, temperature around 36. 2.3. Herbal bath (mugwort). Clear water with a faint brown tint. Temperature around 35. Having a coffee bath is a pretty cool touch worth noting. Otherwise these are old hotel baths with an ocean view. 07.11.2025 09.11.2025