Shihonoyu Onsen (志保の湯温泉)

Introduction: The Poet’s Pearl and the Miraculous Beauty Spring

Tucked away in the quiet, mineral-rich “Town of Stones” (Ishikawa Town), lies the legendary Shihonoyu Onsen (志保の湯温泉). This one-house retreat is the epitome of the “Hitou” (Hidden Spring) experience, steeped in Heian-period romance. According to 1,000-year-old lore, the famed poet Izumi Shikibu (then known as Tama-hime) was born here and cured her childhood skin ailments by bathing in this very spring, resulting in the radiant skin for which she became legendary. Today, the single inn, Shiho no Yu Ryokan, remains a guardian of this alkaline treasure. Shihonoyu is defined by its extraordinary pH level of 9.6—one of the highest in Fukushima—offering a “natural soap” effect that dissolves old skin cells and leaves the body feeling silky smooth. For the international traveler, Shihonoyu provides a profound encounter with Japan’s literary heritage and the silent, restorative power of the Abukuma mountains.

Key Information Table

The Healing Waters: The Science of High Alkalinity

The water at Shihonoyu Onsen is a rare geological anomaly within the Abukuma Highland.

Balneological Properties: Classified as a Simple Cold Mineral Spring, it emerges at a cool 29°C and is heated for a therapeutic soak. Its defining feature is a pH value of 9.6.[13, 12] In balneology, water with a pH above 8.5 is considered alkaline and acts as a natural cleanser, emulsifying skin oils to remove dirt and dead keratin. The result is an immediate sensation of “slippery” skin that feels refreshed and rejuvenated. Additionally, the region is rich in pegmatite and granite, which supply trace amounts of radium/radon, providing a gentle “Hormesis” effect that stimulates the immune system and cellular repair.[12, 16]

Recommended Stay: Shiho no Yu Ryokan (志保の湯旅館)

• The Experience: A peaceful, nostalgic wood-built inn with just 6 Japanese-style rooms. Staying here is like entering a time capsule of the Showa era. The atmosphere is centered on “Toji” (recuperation) and silence, with views of the surrounding forest and the sound of the nearby stream.
• Gastronomy: The inn serves “Satoyama Cuisine,” featuring mountain vegetables, handmade soba noodles, and river fish slow-grilled over embers.

Must-Visit Neighborhood Spots: Cherry Blossoms and Crystals

Ishikawa Sakuradani (Cherry Valley): In mid-April, over 2,000 cherry trees bloom along the Imade and Kitasu rivers, creating a spectacular pink tunnel near the onsen.[17, 18]

Mineral History Museum (イシニクル): Ishikawa is one of Japan’s top three mineral-producing regions. Visit this museum to see giant quartz crystals and learn about the area’s geological richness.[19, 16]

Izumi Shikibu Birthplace: Explore the small monuments and sites dedicated to the legendary poet, located just minutes from the spring.[20, 21]

Culinary Inclusivity: The Brown Rice Haven

For travelers with dietary restrictions, the Ishikawa area is home to Warahana Shokudo (笑花食堂), a dedicated macrobiotic and vegan-friendly restaurant. They serve plant-based meals using local organic vegetables and brown rice, strictly avoiding animal-derived dashi. This makes the region an excellent base for vegan travelers seeking authentic Japanese wellness from the inside out.

Practical Travel Tips for International Visitors

• Tattoo Policy: Small, family-run inns like Shiho no Yu are typically discreet. For larger tattoos, it is polite to use the private family bath or use a cover-up sticker during your visit.
• Connectivity: Expect a “Digital Detox” experience. Mobile signal can be weak in the deep mountain rooms, though Wi-Fi is starting to be introduced in common areas.[22, 23]
• Seasonal Closing: While the inn is generally open year-round, access roads can be icy in winter (Dec–March). Studless tires are required for rental cars during this period.[24, 25]

Safety & Manners

Always wash your body thoroughly before entering the tub. Because the water has a “slippery” texture due to high alkalinity, the bathroom floors are exceptionally slick—walk with extreme caution to avoid slips. Finally, do not take home pebbles from nearby sacred sites, as legend says it brings bad luck to the eyes.