Miyagi Prefecture boasts 749 hot spring sources, making it one of Japan's premier onsen destinations. Among these, the hidden hot springs nestled deep in mountain valleys and along secluded gorges offer truly special experiences for hot spring enthusiasts. This guide introduces 10 secret onsen in Miyagi, ranging from wild hot springs (noyū) to historic healing baths and solitary mountain inns.
1. Fukiage Onsen Houunkaku (Osaki City - Onikobe Onsen)
Located in the remote Onikobe area of Naruko Onsen, Houunkaku is a solitary inn featuring the remarkable "Sennin-buro" (Hermit's Bath). This unique outdoor bath is formed by a natural waterfall created by hot spring water flowing from Jigokudani (Hell Valley).
The waterfall bath, sculpted entirely by nature, has water temperatures that vary significantly by season. The optimal bathing period is from late May to late October, with temperatures around 37°C reported during favorable conditions. In midsummer, temperatures can exceed 50°C, while during the snowmelt season, they can drop to 5-6°C - a completely nature-dependent hot spring experience.
A year-round mixed outdoor bath is also available, offering views of mountain streams. The indoor baths are separated by gender and accommodate 4-5 people. As a true secret hot spring inn, only 8 guest rooms are available.
- Spring Quality: Alkaline simple hot spring
- Source Temperature: 82.5°C
- pH: 8.5
- 100% free-flowing from source
- Baths: Indoor baths=2, Outdoor baths=2 (including 1 mixed bath and 1 waterfall bath)
- Day-use bathing: Available (10:00-13:00, Adults 500 yen)
- Accommodation: Available (8 rooms, reservation required)
- Operating period: Year-round (waterfall bath seasonal)
2. Nakayamadaira Onsen Takuhide (Osaki City)
A renowned inn in Nakayamadaira Onsen, known for its unique spring quality within the Naruko Onsen area. The 300-year-old hot spring, called "unagi-yu" (eel bath), features a silky texture like lotion.
The spring possesses all four elements of beautiful skin baths: "alkaline," "sulfur spring," "sodium bicarbonate spring," and "sulfate spring." With a pH of 9.2, this strongly alkaline water boasts one of the slipperiest textures in Japan.
The inn offers up to 8 different baths for exploration, including the mixed outdoor bath "Tsurukame-no-yu," indoor baths, and private baths, all flowing directly from the source. The 16-room single-story building also features rooms with private outdoor baths.
- Spring Quality: Sulfur-containing sodium-bicarbonate-sulfate spring
- Source Temperature: 67.9°C
- pH: 9.2
- 100% free-flowing from source (no water addition, no heating, no chlorination)
- Baths: Indoor baths=2, Outdoor baths=6 (including mixed bath)
- Day-use bathing: Available (10:30-14:00, 1,000 yen)
- Accommodation: Available (16 rooms)
- Operating period: Year-round
3. Gaga Onsen (Kawasaki Town)
A solitary inn nestled in the remote mountains at approximately 800m elevation on the south face of Mt. Zao. Surrounded by Zao mountains, mobile phone reception is "almost nonexistent," creating an isolated environment that helps visitors forget urban life.
Recognized as one of Japan's three great hot springs for digestive ailments, this spring has been passed down since the early Meiji era with 100% free-flowing water. Drinking the spring water is permitted, allowing visitors to experience its benefits both internally and externally. A unique bathing method called "kake-yu" features 47°C "hot bath," around 40°C "warm bath," and outdoor baths.
All wooden single-story guest rooms are equipped with underfloor heating for comfort even in mid-winter. With no surrounding buildings, visitors can enjoy the slowly flowing "Gaga time" at this true secret hot spring.
- Spring Quality: Sodium-chloride-sulfate spring
- Source Temperature: 64.4°C (bath temperature 43.3°C)
- 100% free-flowing from source
- Baths: Indoor baths=2 (hot bath, warm bath), Outdoor bath=1
- Day-use bathing: Please inquire
- Accommodation: Available
- Operating period: Year-round
4. Aone Onsen Yumoto Fubokaku (Kawasaki Town)
A prestigious inn located at 800m elevation on the slopes of Mt. Hanabusa in the Zao mountain range. With over 460 years of history as a retreat for the Date family, this hot spring was used for therapeutic purposes by Date Masamune, the first lord of Sendai Domain.
As a member of the Japan Secret Hot Spring Association, the inn preserves the authentic charm of hot springs. The bathhouse is acclaimed as artwork-level, with 6 types of baths (including 2 private baths) where visitors can enjoy free-flowing spring water.
With 480+ years of history, this small ryokan with 14 rooms provides attentive hospitality. Every February, the "Aone Onsen Yukiakari" event creates a fantastic landscape with over 2,000 small snow shrines lit with candles.
- Spring Quality: Simple hot spring
- 100% natural hot spring
- Free-flowing from source
- Baths: 6 types including indoor and outdoor baths (2 private baths)
- Day-use bathing: Available
- Accommodation: Available (14 rooms)
- Operating period: Year-round
5. Kamasaki Onsen Mogamiya Ryokan (Shiroishi City)
With over 600 years of history, Kamasaki Onsen is known as "Oshu no Kus uri-yu" (medicinal bath of Oshu) and "Kizu ni Kamasaki" (Kamasaki for wounds). The central establishment is Mogamiya Ryokan, founded in 1789.
The current main building, constructed during the Taisho era, is a dignified three-story wooden structure in pure Japanese style. The interior, carefully maintained by master carpenters and craftsmen, exudes historical depth and warmth.
The spring water, containing iron salt, produces a grayish light brown cloudy bath. True to its "Kamasaki for wounds" reputation, it is said to be effective for cuts, burns, and post-surgical recovery. Despite limited water volume, the inn adheres to traditional hot spring practices without adding water or circulating.
Self-catering rooms (20+ rooms) are still available for long-term spa therapy guests, preserving Japanese hot spring culture.
- Spring Quality: Sodium-chloride-sulfate spring
- Source Temperature: 36.1°C
- pH: 7.1
- Free-flowing from source (heated, unfiltered)
- Baths: Indoor baths=2, Private baths available
- Day-use bathing: Available (10:00-16:00, Adults 500 yen)
- Accommodation: Available (regular rooms and self-catering rooms)
- Operating period: Year-round
6. Obara Onsen Iwaburo Katsurano-yu (Shiroishi City)
A municipal bathhouse standing along the Shiroishi River gorge. This hot spring source, once buried in sediment for many years, was revived in 2004.
The distinctive feature is its cave-like bathing room. After walking about 5 minutes along a riverside promenade from the parking area and paying the 200 yen entrance fee at the reception hut, a different world awaits. Beyond the curtain, wild bathing pools carved from rock appear.
For environmental conservation, shampoo and soap are prohibited as water flows directly into the river. The bathing style involves rinsing off with the provided shower before entering. For just 200 yen, visitors can enjoy the luxury of soaking in a free-flowing rock bath while listening to the stream's murmur.
Nearby walking trails and suspension bridges make post-bath riverside strolls pleasant.
- Spring Quality: Simple hot spring (hypotonic, weakly alkaline, high-temperature spring)
- Source Name: Me-no-yu
- Free-flowing from source
- Baths: Rock baths (separate for men and women, 1 each)
- Day-use bathing: Available (8:00-18:00, Adults 200 yen, Elementary/Junior high students 100 yen)
- Accommodation: Not available
- Operating period: Year-round (occasional temporary closures)
7. Shinyu Onsen Kurikomaso (Kurihara City)
A secret hot spring inn nestled in a beech forest at 600m elevation at the foot of Mt. Kurikoma. Opened in 1720, Shinyu Onsen was considered the "phantom bath" among the five hot springs of Kurikoma, revived by Kurikomaso.
The source is located at the trailhead of Mt. Kurikoma's Ura-gake course, known since ancient times for healing weary pilgrims. With a faint sulfur scent, water flowing for nearly 300 years permeates both body and soul.
The milky white spring water blends well with skin, capturing the hearts of many hot spring enthusiasts. Private baths offer seasonal Kurikoma scenery perceived through all five senses, providing healing moments enveloped in nature.
Meals feature iwana (char) as the main dish. Since fish are prepared from tanks per order, truly fresh, just-fried delicacies are served. Simple local cuisine using mountain vegetables and regional ingredients is also popular. With 8 guest rooms total, this inn adheres to free-flowing springs and traditional Japanese spa culture.
- Spring Quality: Sulfur-containing spring (milky white)
- Free-flowing from source
- Baths: Large public bath, outdoor bath, private bath available
- Day-use bathing: Please inquire
- Accommodation: Available (8 rooms)
- Operating period: Year-round
8. Higashi-naruko Onsen Ryokan Ohnuma (Osaki City)
Located in Higashi-naruko Onsen of the Naruko Onsen area, this renowned spring inn has healed people for 120 years. As a member inn of the Japan Secret Hot Spring Association, it continues to preserve the authentic charm of hot springs.
The main feature is possession of two different sodium bicarbonate springs. The private source is a rare "pure sodium bicarbonate spring" with both sodium and bicarbonate ions exceeding 85%. With pH 7.0 neutrality, the water is gentle on skin with a smooth texture. The other communal source is a transparent sodium bicarbonate spring containing salt, characterized by a soft yet crisp bathing sensation.
The inn offers 8 uniquely characteristic baths, with 5 available as private baths and 4 free of charge. Even solo visitors can leisurely enjoy the hot springs. The garden private outdoor bath "Mori-no-yu" is an exceptional space for bathing while viewing greenery and listening to birdsong.
Water containing ancient plant layer minerals warms the body from its core and remarkably revitalizes skin. The "Tennyo-buro" with metasilicic acid exceeding 270 is beloved by hot spring fans as beauty serum-like water.
- Spring Quality: Sodium-bicarbonate spring (pure sodium bicarbonate spring), Sodium-bicarbonate-chloride spring
- Source Temperature: Approximately 64.9°C, approximately 66.4°C
- pH: 7.0-7.4
- Free-flowing from source
- Baths: Indoor baths=7, Private outdoor bath=1 (total 8 baths)
- Day-use bathing: Currently suspended
- Accommodation: Available (Main building 10 rooms, Spa therapy building 16 rooms)
- Operating period: Year-round
9. Togatta Onsen Area (Zao Town)
A historic hot spring resort said to have opened 400 years ago, located at 330m elevation along the Matsukawa River on the eastern foot of the Zao mountain range. Known for effectiveness on leg and lower back pain, the hot spring town features communal baths "Kami-no-yu" and "Kotobuki-no-yu" where visitors can casually enjoy renowned waters.
The spring quality is sulfate spring, with soft water said to be effective for neuralgia, rheumatism, and gynecological conditions. While source temperature reaches 68°C requiring water addition, free-flowing water is enjoyed.
Legend has it that the severed tail of a great eel from Fudo Falls, defeated in battle with the great crab of Sankai Falls, drifted ashore here, creating a hot spring effective for leg and lower back ailments.
The hot spring town features souvenir shops and kokeshi (wooden doll) workshops, with scenic views of yukata-clad guests strolling about. Approximately one hour by car from Sendai City, it's ideal for day-trip hot spring travel.
- Spring Quality: Sulfate spring (sodium-chloride-sulfate spring)
- Source Temperature: 68°C
- Free-flowing (with water addition)
- Communal baths: Kami-no-yu, Kotobuki-no-yu
- Day-use bathing: Available (communal baths: Adults 250 yen, Children 150 yen)
- Accommodation: Available (multiple ryokan and hotels)
- Operating period: Year-round
10. Kawatabi Onsen Area (Osaki City)
One of the Naruko Onsen areas, this hot spring resort has long been known as "Kakke Kawatabi" (beriberi Kawatabi). The opening dates back to the early Edo period during the Genna-Kan'ei years, with a history of prosperity as a therapeutic spa.
Multiple ryokan dot the hot spring town, each possessing private sources. Spring quality centers on simple springs and sulfate springs, with many skin-friendly waters. Communal baths are available, providing an environment for casually enjoying hot springs.
Being somewhat removed from central Naruko Onsen allows for hot spring enjoyment in quiet surroundings. With rural landscapes spreading around, visitors can experience spa therapy in a peaceful atmosphere at this hidden gem hot spring resort. Inns like "Yama-fukoro no Yado Miyama" offering therapeutic-style stays are also popular.
- Spring Quality: Simple spring, sulfate spring, etc.
- Free-flowing source inns available
- Communal baths available
- Day-use bathing: Available at some inns
- Accommodation: Available (multiple ryokan)
- Operating period: Year-round
Conclusion
Miyagi Prefecture's secret hot springs each possess unique charms. From natural waterfall baths and lotion-like "unagi-yu," to 600-year-old medicinal baths and 200-yen cave baths, diverse hot spring experiences await.
While some locations present access challenges, avoiding crowds and quietly enjoying hot springs represents the true essence of secret hot springs. Please enjoy a hot spring journey refreshing both mind and body away from urban hustle and bustle, surrounded by nature.
*This information represents the latest available at research time but may contain errors. Please confirm the latest information on official websites.