Sayamago Onsen is an alkaline simple thermal spring at pH 8.8, drawn from a 34.4 °C well. The water shows a faint yellow tint, a touch of salt on the lips, and a light hydrogen sulfide note at the source. Mineralization is light (0.419 g/kg), led by sodium and bicarbonate, and the alkalinity gives the water a smooth, slippery feel — it sits squarely in the Japanese 'beauty-water' family.
320. Niji no yu, Osaka
Modern super sento with natural hot spring water, an hour from Osaka station for 880-930. Operating hours listed as 10:00-24:00. They stamp the 41 Kansai Super Sento stamp rally 24/25. Has a restaurant, massage chairs, massage, and a hyperbaric chamber. Private baths available, but the staff said it's better to book two weeks in advance. The main feature of the place is the view of a rocky cliff from the public and private baths, as well as from some windows in the complex.
1. Outdoor area. View of a rocky cliff with waterfalls, trees growing on top. I was there in the evening — the cliff had lighting on. But in the evening, with the lighting, the cliff shape, and the place's trendy atmosphere, the whole picture felt somewhat artificial. Also the view is rather narrow: roof above, building to the right, fence to the left. On a weekend evening it was very crowded, which didn't help the atmosphere.
1.1. Bath in two parts with a view of the rocky cliff and waterfall. Clear water, temperature around 40. One half is a regular bath, the other half is a foam bath. The view from the bath is broken by two fences, so it doesn't feel like an infinity pool.
1.2. Five individual single-person baths, clear water with bubbles, temperature around 40.
1.3. Five individual single-person baths, clear water, temperature around 38.
2. Indoor area:
2.1. Bath with clear water, temperature around 44.
2.2. Bath with clear water, temperature around 40.
2.3. Set of jet baths.
2.4. Electric bath.
2.5. Sauna.
2.6. Cold bath.
Based on Google Maps photos, expectations were much higher, but overall it's a distinctive and unique place. Due to its individuality, worth considering for a Kansai visit.
