Kabukicho, Shinjuku, Tokyo
Shinjuku Natural Onsen Thermae-Yu
A large late-night spa for visitors staying around Shinjuku or travelling overnight, with a transported natural spring, multiple baths, sauna and rest areas. The spring is heated, diluted, filtered and disinfected at the Shinjuku facility; it is not source-flowing there.
Check before bathing
- Opening hours
- Open 24 hours, but the second-floor baths close for cleaning from 03:00–06:00. From 2026-05-01, adult admission is ¥3,100 Monday–Thursday and ¥3,200 on Fridays, weekends, public holidays, specified dates and holiday eves. Staying inside from 00:00–06:00 adds ¥2,000 or ¥2,300 respectively. Rock spa is ¥900 extra. No re-entry after leaving.
- Tattoo policy
- Japanese and foreign residents with tattoos are generally refused regardless of size. Visiting foreign male tourists may qualify for an exception with a ¥330 designated cover sticker and passport or flight ticket; women follow a more permissive trial policy, with cover stickers required above the facility's size limit. Check current terms before visiting.
Spring & water temperature
- Spring-source temperature
- 50.7°C at the Nakaizu supply source; this is not the temperature of the Shinjuku outdoor pool.
- Bathing temperature
- The fixed temperature of the natural spring outdoor pool is not published. Other pools include carbonated water at 38–39°C, white and silk baths around 42°C, jet and reclining baths around 40°C, and a cold bath around 17°C.
- Spring source
- The Shinjuku bath uses transported water from Jindai-no-Yu in Nakaizu, from the Umeki No. 1 and No. 2 mixed sources.
- Spring classification
- The Shinjuku facility lists a sodium-calcium sulfate spring, low-salinity, alkaline and hot spring; pH 9.0.
- pH
- 9.0, as listed by Thermae-Yu for the transported spring. The supply inn publishes different figures, which are not substituted here.
- Flow rate
- Not published for the Shinjuku facility.
- Water handling
- The spring is transported from Nakaizu and then heated, diluted, circulated, filtered and disinfected at Thermae-Yu. Those conditions differ from the source inn's own source-flowing baths. Natural spring water is used mainly in the outdoor Jindai-no-Yu pool; other pools are separate features.
Entry is limited to ages 13 and over. Guests aged 13–17 need an accompanying guardian and must leave by 20:00.
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.
