Hot Springs for Beautiful Skin | Bicarbonate, Chloride & Sulfate Springs Explained

Kamioka Onsen flows on its own, without pumps, from a 170 m well drilled in 1957 in Beppu's Kannawa district. A 2025 analysis recorded 89.5°C and pH 9.0: an unusual alkaline sulfur spring in a town known for acidic sulfur waters, its sulfur dissolved as hydrosulfide ions rather than gas. Sodium 228.0 mg/kg, bicarbonate 279.0 mg/kg, sulfate 184.0 mg/kg and metasilicic acid 339.0 mg/kg give a clear water with a faint sulfur scent and a quiet, deeply comforting character.

Struck in 1979 by a local shopkeeper who drilled 1,020 meters beneath the port town of Shari, at the base of the Shiretoko Peninsula, this source rises through the peat beds under the Shari Plain. That journey gives it plant-derived humic matter and a pale amber tint, placing it among Hokkaido's celebrated moor springs. Bicarbonate makes the alkaline water feel soft, while a faint saltiness hints at the nearby Sea of Okhotsk. It has long served locals and working travelers as an unpretentious everyday bath.

Nestled quietly in the mountainous region of Toyama Prefecture, Ogawa Onsen gushes forth. This naturally gushing spring, cherished by locals for generations, delivers the pure blessings of the earth. Its mild, neutral waters gently embrace the body, while a subtle veil of salt ensures a restorative warmth that lingers. Guests will also experience the benefit of silky skin, feeling remarkably light and refreshed after their soak. It is highly recommended for those seeking deep relaxation from daily fatigue, and those desiring gentle comfort for cold sensitivity or gastrointestinal discomfort.

This is a newly drilled source in the Yufuin Onsen area, which boasts one of the largest outputs in Japan. Nestled at the foot of Mt. Yufu, this hot spring resort has long been cherished for therapeutic bathing. The AMBER Yufuin source features a high alkalinity of pH 8.9, combining the qualities of a bicarbonate spring that smooths the skin by removing old keratin, and a chloride spring that helps retain body heat. It is particularly characterized by its abundance of metasilicic acid, a natural moisturizing component.

Usuki Onsen was drilled to 1,300 m near the old castle town of Usuki, long known as a place without hot springs. Formerly called a "bicarbonate-salt spring", it emerges colorless and clear with a faint salty taste. Its weakly alkaline bicarbonate softens the skin surface for a remarkably slippery feel, while the chloride keeps warmth lingering after the bath. It suits travelers who want to warm up gently after strolling the stone Buddhas and castle-town lanes.

Pumped from 1,000 meters beneath the Kuju Highlands in Aso-Kuju National Park, the Tenku no Daichi Kuju Kogen Hotel source is a true all-star spring, combining the properties of chloride, sulfate, and bicarbonate waters. Rich in metasilicic acid, a natural moisturizer, it leaves skin feeling smooth during the bath and wonderfully soft afterward. It's perfect for days when you want to deeply soothe body and soul while gazing at the majestic nature of the Kuju mountain range and Mount Aso.

Iwanai Onsen spreads across the heights of Iwanai, a town facing the Sea of Japan, at the foot of Mt. Iwanai in the Niseko range. The town-owned Well No. 5 is pumped at a generous 290 L per minute and supplied to inns such as Takashima Ryokan below. The water is clear and nearly tasteless and odorless, with a balance of bicarbonate and chloride, and its smooth touch has earned it a reputation as a skin-beautifying bath. At Takashima Ryokan the source flows straight into the indoor bath and a wooden outdoor tub, where fine bubbles rise through the fresh water.

The Mandaiko source, originating from traces of past mining development, is deeply intertwined with Kusatsu Onsen's unique yumomi culture and its long history of toji (therapeutic bathing). Its highly acidic waters, among Japan's most potent, deliver a distinctive tingling sensation, awakening both mind and body and offering a sense of rejuvenation. The high-temperature blessings penetrate deep into the core, leaving you with a surprisingly light and refreshed feeling after your bath. We invite those seeking a genuine toji experience, a true escape from daily life to restore their mind and body, to discover the profound power of this spring.

This unique created hot spring utilizes the fumaroles of Owakudani, which were formed by volcanic activity approximately 3000 years ago. In the early Showa period, Hakone Onsen Kyokyu Co., Ltd. developed this source to supply hot water to areas like Sengokuhara and Gora. The water, created by mixing volcanic gas and water, offers a distinct, tingling, and tightening sensation upon contact with the skin. The powerful energy from the earth delivers restorative warmth deep into the body, a warmth that lingers long after your bath. It is ideal for those seeking deep relaxation and rejuvenation, wishing to refresh their mind and body.

This renowned hot spring of Jozankei Onsen traces its origins to a legend from 1897, where a wild deer was said to have healed its wounds on the banks of the Toyohira River. Rich in salt, the waters gently envelop the skin like a protective veil, delivering a soothing warmth that penetrates deep into the body's core. The pleasant, lingering warmth after bathing feels akin to being embraced by nature's blessings. This source offers a serene retreat for those seeking to unwind from daily fatigue while listening to the tranquil murmuring of the valley.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

The Yubatake source, naturally gushing from Kusatsu Onsen's iconic Yubatake (Kusatsu's central hot-water field), holds a distinguished history. During the Edo period, it was ranked as the highest-ranking Ozeki in the Onsen Banzuke, recognized alongside the Shirahata source as one of Kusatsu's two major hot springs. Its powerful, pH2 water, permeated with a sulfurous aroma, imparts a refreshing, tightening sensation upon the skin. A soak in this historic, renowned hot spring cleanses the body and mind, offering deep relaxation and rejuvenation from daily fatigue. It is a must-visit for those seeking to feel the energy of a historic hot spring and desire a complete refresh.

Counted among Kusatsu's historic "Twelve Baths" since the Edo period, Kunshi no Yu is said to have been named in the Kan'ei era and still bubbles up west of the Yubatake, toward Sainokawara. Flowing naturally at 64.7 liters per minute, its clear water carries drifting white mineral flakes and a gentle sulfur aroma that distills the essence of Kusatsu.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

Motonoyu is the shared source of Hanashiki Onsen, welling up beside the confluence of the Shirasuna and Nagasasazawa rivers and managed by the local Iriyama Hanashiki property association. Legend says Minamoto no Yoritomo named the spa after mountain flowers reflected on the water, like a carpet of blossoms. The clear water carries a faint hint of sulfur, soothes the skin and lets warmth linger long after bathing, ideal for unhurried soaks to the sound of the mountain stream.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

This renowned hot spring of Jozankei Onsen traces its origins to a legend from 1897, where a wild deer was said to have healed its wounds on the banks of the Toyohira River. Rich in salt, the waters gently envelop the skin like a protective veil, delivering a soothing warmth that penetrates deep into the body's core. The pleasant, lingering warmth after bathing feels akin to being embraced by nature's blessings. This source offers a serene retreat for those seeking to unwind from daily fatigue while listening to the tranquil murmuring of the valley.

The Koganezaki Furofushi Onsen source gushed up in 1970 when a well was bored 200 meters beneath the shore of Koganezaki, and its name expresses the wish that those who rest here will neither age nor weaken. Clear at the moment it emerges, the water oxidizes into a rust-red hue as its iron meets the air, while its dense salts wrap the body and let warmth linger deep inside. It soothes travelers who want to unwind slowly while the sun sinks into the Sea of Japan.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

Shirogane Onsen began in 1950 when drilling in Biei struck scalding water, and the mayor of the day is said to have likened it to precious platinum rising from the earth, giving the spa its name. This source blends four wells, No. 14, 15, 18 and 19, in the national forest of the Shirogane district and supplies inns along the Biei River gorge. In the tub it turns a cloudy yellow-green, first slippery and then slightly squeaky on the skin, and it has long been called the "cane-forgetting spring," suiting those who want to warm to the core beside the sound of the gorge.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

Discovered in 1992, Kumihama Onsen, drilled from 1500m underground, emerges in the scenic Kumihama Bay area of northern Kyoto Prefecture, facing the Sea of Japan. Its colorless, transparent, and mild waters are renowned for a gentle, skin-enveloping veil of salt. This unique quality delivers restorative warmth deep into the body's core, ensuring a lasting sense of comfort long after you leave the bath. It's an ideal retreat for those seeking deep relaxation and a profound escape from daily life amidst stunning rias coastlines.

The Atagoyama Sengen, gushing forth in Arima Onsen—one of Japan's three ancient hot springs—is a prime example of the "Kinsen" (gold spring), which turns a vivid reddish-brown upon contact with air. Its history is deep, having long supported the therapeutic bathing culture of Arima. The water from this source, rich in salt and iron, offers a powerful warmth that heats the body to its core. Steeping in this bath envelops you in a warmth that feels infused with the earth's blessings, a sensation that lingers long after you emerge.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

The Yubatake source, naturally gushing from Kusatsu Onsen's iconic Yubatake (Kusatsu's central hot-water field), holds a distinguished history. During the Edo period, it was ranked as the highest-ranking Ozeki in the Onsen Banzuke, recognized alongside the Shirahata source as one of Kusatsu's two major hot springs. Its powerful, pH2 water, permeated with a sulfurous aroma, imparts a refreshing, tightening sensation upon the skin. A soak in this historic, renowned hot spring cleanses the body and mind, offering deep relaxation and rejuvenation from daily fatigue. It is a must-visit for those seeking to feel the energy of a historic hot spring and desire a complete refresh.

Nestled in the Hakone Yumoto area, Yumoto Onsen (a blend of sources No. 12, 72, 84, 89, 99, and 112) is a luxurious fusion of six distinct springs. It symbolizes the abundant water volume of Yumoto, which historically thrived as one of the ancient Hakone Seven Hot Springs. The chloride spring water, enveloping the skin like a delicate veil, delivers restorative warmth deep into the body's core. The lingering, cozy sensation after bathing gently promotes deep relaxation, easing away daily fatigue. This spring is recommended for those seeking to deeply warm their body and mind and indulge in tranquil moments.

This spring sits high in Kankaiji, one of Beppu's eight hot spring districts, and blends two sources through a mixing valve: the Sugi-2 well and a source at the Minamitateishi geothermal power plant, a very Beppu way of using the earth's heat for both power and bathing. Emerging at 91.4°C, its anions are 64 percent chloride and 21 percent sulfate with plenty of carbonate, giving a mildly alkaline water. Clear and faintly salty, its abundant metasilicic acid lends a soft, gentle feel.

Named after a peak resembling Switzerland's Weisshorn, this spring in the hills of Kyowa was discovered in 1968 by a borehole drilled to explore metal ore deposits. As the flow declined, a 731 m No. 2 well was drilled in 1975 and an 848 m No. 3 well in 1979, and the two are now blended. The alkaline chloride-sulfate water leaves skin feeling smooth, suiting drivers on the national highway who want to soak away a long journey.

Hakone Yumoto Onsen's history is said to date back to the Nara period, making it Hakone's oldest hot spring village. [2, 4] The Hakone no Yu Kamon source is a private spring drilled in this historic land. This sodium/calcium-chloride/sulfate spring follows in the tradition of famous waters once presented to the Shogun's family during the Edo period. [10] Its waters gently envelop the skin, providing a characteristic warmth that lingers long after bathing. It is recommended for those seeking to release mind and body in historic, nature-rich Hakone.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

Naturally gushing from the riverbed and banks of the Toyohira River, which flows through the heart of Jozankei Onsen, this source's waters are collected without mechanical pumps. Its pristine freshness, embodying the earth's blessings, is truly captivating. A gentle, saline veil envelops the skin, delivering restorative warmth deep into the body's core, ensuring a blissful, lasting afterglow. It's an invitation for those who yearn to be embraced by nature's vigor and experience deep relaxation from the depths of their mind and body.

This private spring in Nozawa Onsen first served a humble bathhouse for therapeutic stays in the Taisho era. Sulfate is its main component, joined by chloride, calcium and hydrosulfide, giving a mineral-rich water whose color shifts from lapis blue to milky white with the seasons and the hour. Because the freshly emerged water flows straight into the baths, it keeps its freshness. Long favored by guests seeking relief for cuts and bruises, it suits travelers who want to rest their bodies slowly and deeply.

Shima Onsen, whose name is said to promise relief from "forty thousand ailments," has long been known as a curative spa for the stomach. This source blends six springs in the Yamaguchi district along the Shima River, all rising to the surface without pumps. The 51.7°C water is clear and colorless, building white, coral-like deposits on spouts and bath rims. It feels squeaky on the skin yet leaves it soft and moist, ideal for those who want water exactly as it emerges, to the sound of the river.

Kinosaki Onsen's centrally managed mixed spring gathers water from several wells into a large storage tank, where its temperature is steadied before it flows through a looped pipe beneath the streets to the town's public bathhouses and inns. Managed as a shared resource by the Yushima property ward of Kinosaki, this faintly salty water wraps the body in warmth that lingers long after bathing, suiting travellers who stroll from bath to bath in yukata.

Hot springs in Shinshinotsu began with the No.1 well drilled in 1990, whose water had to be heated. In 2015 the No.3 well, reaching 1,600 m, was completed, delivering water above 50°C ready to use. Rising beneath the Ishikari Plain beside oxbow Lake Shinotsu, it is a yellowish-brown, intensely salty water with a faint medicinal note from iodine and bromine. Its dense salts wrap the skin and keep you warm long after bathing, a fine companion for harsh winters.

Shirahatage Genzen, located in Kusatsu Onsen and adjacent to Yubatake (Kusatsu's central hot-water field), is said to have been discovered by Minamoto no Yoritomo. Historically, it served as the stage for 'Jikan-yu' (timed bathing), supporting balneotherapy culture, and is truly considered the soul of Kusatsu. Its distinctive aroma and powerful waters, which feel as though they firm the skin, seem to awaken the mind and body from within. Surrendering to its embrace offers a pure moment to shed daily clamor and rediscover one's true self. This spring is a sanctuary for those seeking a fresh start and rejuvenation.

The Kowakien Kyokyu Onsen is a steam-generated spring developed since 1949 to supply the Hakone Kowakien resort area. It utilizes geothermal heat from former fumarolic activity along the Kurumazawa stream, a tributary of the Jakotsu River, blending multiple sources and natural spring water. This source is widely distributed to the various facilities of the Hakone Kowakien resort, operated by Fujita Kanko, forming the foundation of the entire resort.

The Mandaiko source, originating from traces of past mining development, is deeply intertwined with Kusatsu Onsen's unique yumomi culture and its long history of toji (therapeutic bathing). Its highly acidic waters, among Japan's most potent, deliver a distinctive tingling sensation, awakening both mind and body and offering a sense of rejuvenation. The high-temperature blessings penetrate deep into the core, leaving you with a surprisingly light and refreshed feeling after your bath. We invite those seeking a genuine toji experience, a true escape from daily life to restore their mind and body, to discover the profound power of this spring.

Ishida Onsen's source flows naturally on the flanks of Mt. Esan, an active volcano, and is piped about 2.5 km down, inheriting the spring once used by a highland hotel. The 1984 analysis shows pH 2.1 and 5.518 g/kg of dissolved solids, with 2,972 mg/kg of sulfate plus abundant aluminum and iron, in the lineage of classic alum and green-vitriol springs. Clear at the source, the water oxidizes to a cloudy yellow-brown in the bath, with a squeaky feel, sour taste and metallic scent that speak of the volcano.

The Taenoyu Onsen (Kin no Yu) source gushes naturally in the gorge of the Sendatsu River that runs through the Nyuto Onsenkyo, and it earns the name "golden water" as its iron shifts from gold to deep brown on meeting the air. At pH 2.9 its acidic water tightens the skin while its sulfates let warmth linger in the body. It suits travelers who wish to restore body and mind in a spirited spring to the sound of the mountain stream.