Miyagi · Naruko Onsen
Nakayamadaira Onsen Shintoro-no-Yu (Naruko Onsen-kyō)
中山平温泉 しんとろの湯（鳴子温泉郷）
A public bath at Nakayamadaira Onsen, at the western end of the Naruko onsen cluster. High-temperature source water is run through a wooden flume about 200 m long to cool it naturally, with no added water and no recirculation. At pH 9.4 it is alkaline, and the silky feel is where the name 'Shintoro' comes from. Open 9:00–20:30 (last entry 20:00) with no closing day, at ¥500 for adults, ¥250 for elementary pupils and free for younger children. There are separate indoor baths for men and women; lockers cost ¥100. Towels are sold for ¥400 and bath towels for ¥700. A local-produce shop, Yunokei Shintoro, shares the grounds.
- Price (adult)
- ¥500
- Hours
- 09:00–20:30(last entry 20:00)
- Closed
- Open daily
- Access
- 15 minutes on foot from Nakayamadaira-Onsen Station on the JR Rikuu East Line; 35 km and 50 minutes from Furukawa IC on the Tōhoku Expressway via Route 47
- Water type
- Sulfur spring
- Tattoos
- Ask ahead
- Admission
- Adults ¥500, elementary pupils ¥250, pre-school children free. Lockers are ¥100; towels are sold for ¥400 and bath towels for ¥700 (sold, not rented). Soft-boiled onsen eggs are sold at Yunokei Shintoro on the same grounds.
- Spring water
- A sulphur-bearing sodium bicarbonate-chloride spring (hypotonic, alkaline, high-temperature) at pH 9.4, strongly alkaline. Its feel is silky like the white of an onsen egg, and that texture gave the place its name. The source is close to 100 °C and unusable as it is, so it is run through a wooden flume some 200 m long to cool naturally.
- Baths
- The layout is tidy, with one indoor bath for men and one for women. There is no rotenburo and it is mostly indoors, but the windows look out on the hills and trees of Naruko. Toiletries, shampoo and dryers are provided, so a towel is all you need. A rest space and a shop make it easy to linger after bathing.
- Access & parking
- 15 minutes on foot from Nakayamadaira-Onsen Station on the JR Rikuu East Line, and easy to find by car along Route 47. It is 35 km and about 50 minutes from Furukawa IC on the Tōhoku Expressway via Route 47. The Naruko cluster lines five onsen — Naruko, Higashi-Naruko, Kawatabi, Nakayamadaira and Onikōbe — along Route 47, which makes comparing waters by car straightforward.
- Phone
- 0229-87-1126
- Open in Google Maps
- Google Maps ↗
Essentials
Stay in this onsen town
Compare and book stays in Naruko Onsen. Day bathing itself needs no booking.
Opens partner booking site (affiliate)
Why go
- Source cooled naturally in a 200 m flume
- Silky alkaline spring at pH 9.4
- ¥500 and open daily
Silky water cooled along a 200 m wooden flume
Shintoro-no-Yu is a public bath at Nakayamadaira Onsen, at the western end of the Naruko cluster. The water here rises at close to 100 °C and cannot be entered as it is. So the facility runs the source through a wooden flume some 200 m long, letting air and timber lower the temperature naturally. Water cooled that way, without pumps or cooling plant, reaches the tub with the silky feel of a pH 9.4 alkaline spring intact. At ¥500 for adults, open daily from 9:00, it is an easy first stop on a round of Naruko.
What makes it smooth, and what to watch for
A pH of 9.4 is highly alkaline even by onsen standards. Such water softens and dissolves old skin and oil, so dipping a hand in feels slippery, as if soap had been applied. Because of that action, people with sensitive skin can smart after a long soak, and rubbing the eyes stings. After getting out, drink plenty of water and avoid rinsing the eyes. Metal jewellery can discolour, so removing it before entering is safer.
A starting point for driving the Naruko spa group
The Naruko cluster is not one onsen but five lined along Route 47. Naruko proper smells strongly of sulphur; Higashi-Naruko has many milky baths; Kawatabi is known for drinking the spring; Nakayamadaira is strongly alkaline; and Onikōbe lies deep in the mountains. The waters differ greatly. Shintoro-no-Yu sits in Nakayamadaira and opens at 9:00 every day, which makes it a good starting point for a round. Without a car it is 15 minutes on foot from Nakayamadaira-Onsen Station, or about 10 minutes west along Route 47 from Naruko-Onsen Station.
Before you go
- No official tattoo policy is published — ask at reception.
- The water runs hot (43–45°C). Don't add cold water; take short repeated dips instead.
- Payment is usually by ticket machine in cash — bring coins.
- Last entry is 30–60 minutes before closing.
Features
Price
Convenience
Amenities
✔ Verified operating: 2026-10 Operating status and rates cross-checked against the official site and onsen guides (full source notes in Japanese on the JA page)
Prices and hours change. Check official sources before visiting.
More in this area
Taki-no-Yu, Naruko
A communal bath with over a thousand years of history as the shrine's sacred spring. Milky acidic sulfur water pours like a waterfall from log flumes into cypress tubs. ¥300; bring your own soap.
Naruko Waseda Sajiki-yu
A communal bath using a spring that Waseda University students struck during fieldwork in 1948. Architect Osamu Ishiyama's yellow avant-garde building is unmistakable; descend the stepped 'sajiki' gallery to the bathroom. The modern counterpart to Taki-no-yu.
Akiu Onsen Public Bath
The only communal bath in Akiu Onsen, Sendai's classic hot-spring retreat. Among upscale ryokan charging ¥1,000-plus for day use, this humble bathhouse offers free-flowing chloride spring water for ¥300. Near the Yakushi-do temple at the source, it has a single tub and a mostly local crowd; soap is sold, not provided, and a sign asks for 40-minute stays. About 55 minutes by bus from Sendai Station, right by the Yumoto stop.
