Someino, Sakura, Chiba
Sakura Natural Onsen Sumire
A broad bathing and sauna complex whose clearest source-water feature is the source-flowing outdoor rock bath. Other pools have separate water conditions, so the whole facility should not be described as source-flowing.
Facility photos
Check before bathing
- Opening hours
- Open 07:00–24:00; last entry 23:00. Adult admission is ¥1,050 on weekdays and ¥1,200 on weekends and holidays. Closed on the second Thursday of March, June, September and December; the September 10, 2026 closure has passed.
- Tattoo policy
- The operator refuses guests with tattoos or tattoo stickers regardless of size. No cover-seal or small-area exception was listed.
Spring & water temperature
- Spring-source temperature
- 2026°C
- Bathing temperature
- The source-flowing rock bath is listed at 41–42°C, with a seasonal cool setting around 36°C. The operator also lists 40–41°C for the main spring bath; these are bath settings, not source temperatures.
- Spring source
- Sakura Someino Onsen.
- Spring classification
- Iodine-bearing sodium chloride strong-salinity spring; high concentration, weakly alkaline and low-temperature classification.
- pH
- 7.54 in a 2026 operator release.
- Water handling
- The operator confirms that the outdoor rock bath is source-flowing and that the indoor main bath uses the spring. Water treatment for other spring baths is not fully detailed pool by pool.
- Analysis date
- 2026
A current source temperature and yield were not confirmed. The operator's tattoo policy refuses tattoos and tattoo stickers regardless of size; no cover-sticker exception was listed.
How to read a bath profile
Spring-source temperature and actual bathing temperature are kept separate. Each score is shown independently for comparison rather than collapsed into one overall score.
