Skin Infections (Pyoderma) & Onsen | Strong Antimicrobial Action of Acidic and Sulfur Springs

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.

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.

This rare, naturally gushing source emerges from beneath 'Gensenkaku,' nestled beside Kusatsu Onsen's iconic Yubatake (Kusatsu's central hot-water field). Despite its strong acidity, its waters offer a remarkably soft bathing sensation, akin to being enveloped in silk floss. The milky-white waters, renowned for having Kusatsu's finest 'yunohana' (hot spring minerals), gently embrace the skin, contributing to silky skin and providing a restorative warmth that lingers deep within the body. Known as a 'phantom spring' for its history of disappearing once during the Taisho era, it now offers a profound escape from daily life, inviting deep relaxation and rejuvenation.

The Bandaiko source, which unexpectedly erupted from within the Bandai Sulfur Mine in 1970, now stands as Kusatsu's primary hot spring, boasting the largest output and supporting the town. Named with the wish for 'eternal prosperity' (万代), this powerful source was born in the mountains, far from the Yubatake (Kusatsu's central hot-water field). Its colorless, transparent waters deliver a stimulating tingle that awakens both mind and body, while its robust warmth permeates to the very core. This energetic spring is a perfect companion for those seeking liberation from daily routines and a crisp mental and physical rejuvenation.

Obuki is the roaring source at the heart of the steaming geothermal field of Tamagawa Onsen, on the southern slopes of Hachimantai. Its output from a single vent is often said to be the largest in Japan, and the fumarole field around it has long produced mineral deposits and the rare hokutolite stone. Every bath in the spa draws on this one source, served either straight or cut with fresh water. At pH 1.13 the water tingles sharply on the skin while warming the body to the core, and it has welcomed long-stay therapeutic bathers for generations, a spring for those who want to meet nature at full strength.

The Oyu source of Shimofuro Onsen carries a sulfur scent so strong that the place name is said to come from the Ainu word "shumafura," meaning "smelly rock." Recorded as "Yumoto" on a Muromachi-period map and bathed in by a Nanbu domain lord in 1656, this pH 2.4 acidic water turns milky as its sulfur flakes swirl, leaving a brisk, tightening touch and a lingering saline warmth. It suits those who wish to steep quietly in a strong sulfur spring within a port town that once thrived as a herring fishermen's spa.

Originating from the fumaroles of Owakudani, born from the eruption of Hakone volcano approximately 3,000 years ago, this artificially developed hot spring began to be supplied to Sengokuhara and Gora by Hakone Onsen Kyokyu Co., Ltd. in Showa 5 (1930). Its renowned milky white waters, blended with naturally gushing spring water, offer a pleasant sensation that tightens the skin and a powerful restorative warmth that penetrates deep into the body's core. After bathing, you'll feel surprisingly refreshed and light. It's a perfect companion when you seek to feel the Earth's energy and achieve deep relaxation and rejuvenation for your mind and body.

This spring rises at a spa retreat about 900 m up the northwest flank of the Hakkoda Mountains, amid beech forest, in the area chosen as Japan's first National Health Resort Hot Spring. It has long filled a great bathhouse built entirely of hiba cypress alongside the area's other springs. At pH 1.71 it is strongly acidic, with a tingling bite on the skin and a faint scent of sulfur and iron; sinking into its milky water feels like the essence of a traditional healing spa, especially in deep-snow winter.

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.

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.

Originating from the dramatic Jigokudani (Hell Valley), the potent waters of Noboribetsu Onsen, a renowned hot spring resort in Hokkaido, have long welcomed those seeking therapeutic benefits. This powerful spring gently envelops the skin, delivering restorative warmth that penetrates deep into the body's core. The comforting heat lingers long after bathing, promoting deep relaxation and offering respite from the stresses of daily life. It is highly recommended for individuals desiring an authentic balneotherapy experience in Japan's northern frontier.

Dake Onsen's association source feeds a spa village said to have opened in 1674. Its self-flowing water is piped several kilometers down from the slopes of Mt. Iwaki, and the local association flushes sulfur deposits from the pipes every month. Listed in Edo-period hot spring rankings, its sharply sour, sulfurous water suits travelers seeking an old-fashioned toji retreat.

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.

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.

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.

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.

The Nuruyu source has been known since the Kyoho era (1716-1735), welling up at about 920 m on the eastern foot of Mt. Azuma-Kofuji. This acidic sulfate water carries iron and aluminum, emerging colorless and turning yellowish-white after a day. Though only 31.8°C, it lets warmth linger slowly in the body, leaving skin cool and smooth. It suits summer bathers and anyone who loves long, unhurried soaks in a water traditionally prized for the eyes.

Esan Onsen Ryokan sits in Kashiwano, Hakodate, at the foot of the active volcano Mt. Esan, and keeps the air of a traditional healing inn. It is said to have begun when an earlier generation gathered the springs they found into a hand-dug basin, and today the naturally flowing source still pours from a single inlet into wooden tubs and over their edges. The water is nearly clear with a faint yellow-green tinge, a scent of iron and a sharp acidity, and white deposits form around the inlet. It is a strongly acidic sulfate spring rare in Hokkaido, and because the water is lukewarm the inn closes in winter.

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 source rises in Konya Jigoku, a steaming "hell" of Myoban Onsen, one of the Beppu Hatto hot spring areas, where sulfur-rich fumaroles drift over the ground. With pH 2.9 and abundant sulfate, the bluish milky water turns grey in shadow and leaves a crisp, tightening touch on the skin. The scent of sulfur lingers long after bathing, making it a favorite for travelers who love cloudy, characterful waters and a refreshing soak.

The Yuhanazawa No.3, No.5 and No.6 Combined Source gathers three springs welling up in the Yuhanazawa district of Takayu Onsen, a spa said to have opened in the Keicho era and once counted among the "Three Takayu of Oshu" alongside Zao and Shirabu. Tart at pH 2.6 and scented with powdery sulfur, its water gushes from the spouts in a blizzard of white mineral flakes, steeping the tubs in a milky blue. It suits travelers seeking a genuine mountain sulfur soak.

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.

The Hinazakura source is one of several springs pumped from the national forest at the far end of Nyuto Onsen, an area named for the crabs that live in its mountain streams. Here each bathhouse draws on its own source, so the waters share a type yet differ subtly in their minerals. Rare among Nyuto's milky springs, this one runs clear, with a slight silkiness, drifting white mineral flakes and a gentle sulfur scent that soothe the skin, a spring for anyone who wants to linger quietly above the beech forest.

The Kashio no Yu No. 1 source draws seawater-strength brine from the heart of the Southern Alps, far from any coast, and the place name Kashio, "deer salt," is said to recall deer that gathered to lick the salty water. For generations this brine has been boiled down to make mountain salt. Its dense salts and gentle sulfur aroma wrap the body, letting warmth linger long after the bath. It soothes travelers who wish to steep quietly in a rare salt spring deep in a mountain village.

Amagase Onsen is one of Bungo's three great hot springs, alongside Beppu and Yufuin. The Ukihabekan Shinshiyo source is drawn via a 150-meter deep powered drill from a hillside site. With over 1,300 years of history, Amagase's waters were mentioned in the ancient "Bungo Fudoki" chronicles and have long been cherished for therapeutic bathing. This source combines pH 8.9 alkalinity with sulfur properties, gently removing old skin cells for a smooth feel. You can enjoy a silky skin sensation after bathing, perfect for those seeking to refresh mind and body.

Emerging from a tea field near the gate of Kurama-dera Temple in Kyoto's "inner parlor" during the late Meiji era, this rare and esteemed hot spring offers subtly sulfur-scented waters. Its gentle, weak alkaline touch smoothly envelops the skin, leaving it with a silky feel. After bathing, a refreshing lightness of body and mind promotes rejuvenation. It provides deep relaxation, helping to relieve pain from journeys exploring Kifune Shrine and Kurama-dera Temple, allowing visitors to deeply refresh amidst the beauty of nature through the four seasons.

Hirugami's waters famously burst forth in 1973 during railway tunnel construction. Wells No. 2 to 5 followed, and today their blended "new mixed spring" is centrally managed and piped to the inns of the valley. At pH 9.8 it is strongly alkaline, giving the skin a slippery, silky feel, with a faint sulfur scent and gentle sweetness.

Sounkyo Onsen traces its roots to the Shioya hot spring opened beside the Ishikari River in the early Taisho era. The Katsura no Yu 1-2-3 mixed source wells up naturally at about 79°C from only two meters underground, is stored in a tank and piped along the mountainside to the baths. Softly scented with sulfur and silky on the skin, it leaves bathers feeling light, a fine companion for travelers unwinding beneath the gorge's towering cliffs.

Kintaro Onsen gushes in Tenjinno, Uozu, close to Kurobe-Unazukionsen Station on the Hokuriku Shinkansen, where the edge of an alluvial fan looks up to the Tateyama range. The Kintaro Onsen source unites the qualities of a chloride spring and a sulfur spring: a dense, hypertonic water holding 4790.0 mg/kg of sodium and 1401.0 mg/kg of calcium, with thiosulfate and free hydrogen sulfide lending a sulfur scent. White and grey mineral flakes drift through the water, suiting bathers who want a hot, deeply warming soak and lovers of both salt and sulfur.

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.

Bessho Onsen No.4 Source is one of the springs of Bessho Onsen, a 1,400-year-old spa some link to the "Nanakuri no yu" praised in The Pillow Book, and it is said to feed the drinking fountain at Kitamuki Kannon temple. Nearly clear, the water carries a toasty sulfur aroma and an alkaline softness that wraps the skin in a slippery smoothness. It suits travelers who want a quiet soak at the gate of an ancient temple.

Nestled in Noboribetsu Onsen, famously called the "Department Store of Hot Springs" and rooted in the Ainu "Nupur-pet" (deeply colored river), the historic "Uma no Yu" source has flowed since Taisho 6 (1917). Its faint sulfur aroma gently unwinds the mind and body. The waters, softly enveloping the skin, warm the body to its core, providing restorative warmth that lingers. Overlooking a beautiful Japanese garden, this tranquil spring offers deep relaxation, a serene escape from daily commotion.

Okudogo No. 4-1 Gensen is drawn from the gorge upstream along the Ishite River from Dogo's historic spa town. Its lukewarm 38.7°C water is alkaline at pH 9.4 and pairs hydrosulfide ions with radon, an uncommon combination. A faint sulfur scent and slippery feel suit bathers who like long, unhurried soaks to the sound of the stream.

Shibu Onsen, said to have been discovered by the monk Gyoki in the Nara period, is home to the No.1 Boring source, which gushes up on its own from a deep borehole at 97.6°C, close to boiling. Nearly clear and carrying a faint whiff of sulfur, the water wraps the body in salty, sulfate-rich warmth yet leaves a light, refreshed feeling afterwards. It suits travelers pausing between cobbled bathhouse visits and anyone seeking deep warmth on a cold mountain night.

Ginga no Yu, Ryusei no Yu and Hoshi no Yu are three springs that gush naturally in the national forest toward Momijidani at Sounkyo Onsen, and the blend of these three sources is piped in together. Sounkyo is a spa set in a gorge of sheer Daisetsuzan cliffs, and this blend, though hotter than 70°C, is neutral and gentle, carrying a faint hydrogen sulfide scent and an eggy taste. Its slippery touch leaves the body light, a soothing sulfur spring for anyone who wants to linger amid the gorge's wild scenery.

Kuroyu is one of four springs of differing character that rise within about 50 meters of one another at Yunotai, said to be the oldest bathing ground of Nyuto Onsen. Long called the "warm-pool spring" and the "spring of fertility," it has the highest chloride content of the four, so a soak warms you to the core and the heat lingers long afterward. The cloudy, sulfur-scented water comes up hot and is tempered with fresh water in some seasons, a robust spring that shows its true worth during deep-snow winter stays.

Known for some 1,700 years and said to be one of Takeda Shingen's hidden baths, Umegashima is a mountain toji village at the head of the Abe River. The city manages the spring and distributes it to the inns. Clear yet scattered with white yunohana, its pH 9.4 alkaline water feels silky and slippery, long praised as a "bath that makes beauties" and ideal for slow, lukewarm soaks.

The Shiroyu source is one of four springs of differing character that rise within about 50 meters of one another at Yunotai, said to be the oldest bathing ground of Nyuto Onsen, where records of a spa date back to the Edo period. Long called the "beauty spring" and the "spring for chills," it bubbles up beneath an open-air bath and is also piped to nearby lodgings. Its bluish, cloudy water carries a gentle sulfur scent and a soft, smooth touch, leaving skin supple and warmth that lingers long after a soak, a spring for anyone who wants to unwind slowly in the beech forest.

This spring rises on a plateau wrapped in old-growth beech forest at the foot of Mt. Akita-Komagatake, the gateway to Nyuto Onsen. Unlike the milky sulfur springs that dominate the area, it is a brownish bicarbonate water that leaves the skin slippery and smooth, with a faint tart taste and a hint of iron. It is warmed in the deep-snow winter months, and invites a side-by-side comparison with the area's white sulfur waters while you take in fresh green or autumn leaves.

Shiobetsu Onsen was first claimed in 1901; the Nomura mining company built a staff retreat here in 1960 and opened it to the public as "Ryokan Tsurutsuru Onsen" in 1970. The water blends two wells, Nomura No. 5 and No. 7, which pour into the indoor bath and flow generously into a spacious open-air bath reached by a small bridge. At pH 9.6 it is strongly alkaline with a faint egg-like scent, leaving skin slippery-smooth — "tsurutsuru," just as the name promises.