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Yutopia

ラドン温泉ホテル 湯ーとぴあラドンおんせんホテル ゆーとぴあ

Lodging
Chubu·Yamanashi
055-276-9111u-u.jp

Day Use

Yes
10:00–23:00
¥880

Bathing & Water

Natural onsen water

Uses natural hot spring water

Indoor BathYes

Enclosed indoor bathing area

Cold BathYes

Cold water plunge bath, typically used after sauna

Policies & Services

WashingYes

Shower, wash stations, soap and shampoo provided

竜王ラドン温泉

Ryuo Radon Onsen

Operated by · 株式会社 湯ーとぴあ

塩
Chloride
+ Bicarbonate
Color
faintly yellow-brown and clear
Taste
slightly salty
Odor
faint hydrogen sulfide

Sodium Chloride spring

pH 8.0Weakly alkaline
Composition fingerprint1.4 g/kg dissolved · Hypotonic
Na⁺88
Cl⁻69
◀ CationsAnions ▶
Sodium Na⁺
salt's cation — pairs with chloride to make the water salty.
Chloride Cl⁻
table-salt anion — coats the skin and holds heat in.
Known good for
  • Warmingcold sensitivity
  • Smooth skindry, rough skin
  • Cutsminor wounds

A sodium-led chloride spring with bicarbonate softness layered in. Weakly alkaline and soft on the skin, it sits in the Japanese beauty-water family. The water carries a faint yellow-brown tint, a slight salty tang, and a faint hydrogen sulfide note, and the source also bears a small amount of radon.

Sampled at wellhead·Analyzed Sep 10, 2019·株式会社メイケー·Cert no. M19-3020

Explore the water

Highlights

Utaseyu

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2.0

1 review

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Sergey M
1 year ago

544. Yutopia, Kai, Yamanashi A wild hotel with a radioactive onsen. In the lobby there's some kind of crazy machine, a large cage with a sleeping cat, and a shop selling retro stuff. Visited for higaeri at 880. Higaeri hours are listed as 10:00 to 23:00. They stamp the Yamanashi 100 Onsen book. Bath photos are from the internet, match the real thing. 1. Indoor area. Breathing inside is good. 1.1. Bath with clear slightly yellowish water. Has utaseyu. Temperature around 39-40. 1.2. Cold bath. 2. Indoor area within the indoor area. There's a separate staircase and a sealed door leading to the radioactive section of the onsen. Inside, everything is covered with posters in Japanese, one of them has a medical "+" symbol. Inside there's a bath with clear slightly yellowish water, temperature around 40, with occasional individual bubbles. It's stuffy inside. I think the onsen at Black Mesa in Half-Life looked exactly like this. Very unusual, strange place. For people with radiophobia — better stay away. 11.05.2025

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Last updated July 3, 2026