Private bath available for day-use visitors or hotel guests to reserve
湯
天心の大湯
Tenshin no Oyu Spring
Operated by · 梅本興業株式会社
Sampled at bath inlet
湯
Simple
Classification
Sodium Bicarbonate-Chloride spring
Tenshin no Oyu is a gentle simple thermal spring drawn from a hot 60 °C source, neutral in pH and lightly mineralized at just 597 mg/kg of dissolved solids. What sets it apart is a generous 245 mg/kg of metasilicic acid, which leaves the kind of thin silica film that makes skin feel noticeably smoother afterwards, placing it in the Japanese beauty-water family. The water is colorless, clear, tasteless and odorless, sampled at the inlet of the family bath.
pH
7.30
Neutral
Source temperature
60.0°C
Hot
Tonicity
0.60g/kg
Hypotonic
Free CO₂
26mg/kg
Low
Radon
7.40Bq/kg
Low
色
Color
colorless and clear
味
Taste
tasteless
香
Odor
odorless
Highlights
High silica
Analyzed Oct 20, 2015·公益社団法人 大分県薬剤師会検査センター·Cert no. 大薬検 第7R-2710002号
501. Baien Garden Resort, Yufuin (pt.2) ★★
About the onsens:
4. Public outdoor stone bath. Judging by photos you should be able to see the mountain from the onsen, but it was dark late in the evening, and in the morning I got a Silent Hill effect, which I appreciated more than the mountain view. Clear water, temperature 41.5.
Great place, excellent rotenburo, and very strong private baths. If staying with family in Yufuin, I'd recommend considering this for accommodation.
09.04.2025 10.04.2025
501. Baien Garden Resort, Yufuin (pt.1) ★★
Stayed overnight. Had single dinner and breakfast, served in a separate space. Food overall was decent, maybe breakfast was a bit simple. Lots of guests with families and children. Overall felt like the place is well-suited for staying with a family or large group, both in terms of dining organization and the large private baths.
Plenty of staff: both Japanese and non-Japanese. At dinner, a Japanese staff member with limited English felt very awkward and struggled pronouncing kaiseki dish names. But in terms of expected service for a hotel with heavy traffic, everything was comfortable — they showed me the room, held the dinner start (I needed a slight delay), efficient taxi ordering, fast kaiseki service (despite the English hiccups), and saw me off at checkout. Maybe some extra small talk about taxis.
About the onsens.
1. Left private large outdoor stone bath. No reservation needed, first-come-first-served. The bath has essentially no view — behind a fence — but it's still very cozy and atmospheric. The bottom of the bath is made of stones with different textures: a path runs along pleasant-to-touch stone, while around the path it's rougher, less comfortable stone. Clear water, temperature in the evening 42-42.5.
2. Right private large outdoor stone bath. Practically identical to the left bath. Clear water, temperature in the morning 42.
3. Public indoor bath. Clear water, temperature 41. Breathing inside is good.
09.04.2025 10.04.2025