Chiba Prefecture has no active volcanoes, one of the few prefectures in Japan without one. That rules out the strongly acidic, sulfur-laden baths found at destinations like Kusatsu or Beppu. Instead, the bedrock of the Boso Peninsula formed from an ancient seabed that rose out of the ocean over geological time, and water trapped deep within these layers still rises to the surface across the region, shaping a hot spring culture unlike any other in Japan.
The signature waters here are moor springs and kuroyu (black water), formed as ancient plant matter decomposed underground over millennia. Kameyama Onsen Hotel in Kimitsu City, Kiyomoto in the Yoro Valley (Ichihara City), and Onjuku no Yu in Onjuku Town all produce baths ranging from amber to near-black. Along the coast, Inubosaki Onsen in Choshi City and Shirako Onsen Tokaiso in Shirako Town draw on fossil seawater trapped in strata roughly 10,000 years old. Joint research by the Choshi Geopark and the Chiba Institute of Science has confirmed the age of this fossil seawater through radiocarbon dating, making it a scientifically notable find among Japan's hot springs.
How each facility treats its water varies considerably, and it is worth knowing the difference before you go. Nomizo Onsen Senju no Yu, Benten Kousen, and Shichirigawa Onsen are genuine source-fed baths, drawn straight from the ground without dilution or recirculation. Shirako Onsen Tokaiso, by contrast, dilutes, heats, filters, and chlorinates its water. At Kameyama Onsen Hotel, Inubosaki Onsen, and Chikura Onsen Chikurakan, treatment differs from bath to bath within the same facility, and Kiyomoto draws on its own private kuroyu source without disclosing whether the water is diluted or recirculated.
Rather than a single headline "hidden hot spring" destination, Chiba rewards visitors who compare each bath on its own terms. Below are 9 of the prefecture's most distinctive hot springs.
1. Nomizo Onsen Senju no Yu (濃溝温泉 千寿の湯) — Kimitsu City
Nomizo Onsen Senju no Yu is a quiet day-use hot spring tucked just behind the entrance to Shimizu Gorge Park in Sasa, Kimitsu City, Chiba Prefecture. It sits directly behind Nomizo Falls and the Kameiwa Cave, a nearby spot famous on social media for the heart-shaped reflection created when morning light streams through the rock tunnel and hits the water's surface. The bath draws its water from a spring that rises naturally from the bed of the Sasa River, a small but treasured facility that the local community has maintained for many years.
The spring is classified as a sodium bicarbonate spring, known in Japanese as jutansan soda-sen, with a mildly alkaline pH of 8.63. At just 15.5°C, the source water is closer to a cold mineral spring in temperature, yet its mineral content is rich enough to qualify as an official onsen under Japan's Hot Spring Law. The water is heated for bathing but never diluted, run through a circulation filter, or chemically treated — a genuine source-fed, continuously flowing bath that has become rare in heavily developed Chiba Prefecture. Living up to its reputation as a 'beauty-skin bath,' the faintly yellow-tinged, clear water leaves skin feeling silky smooth, with a subtle, earthy mineral scent.
The bathing room is a simple, unadorned indoor bath centered on a single stone-lined tub, with a washing area just in front of it — a modest layout that lets the character of the spring water speak for itself. A private reservable bath is also available for those who prefer to soak without company. The spacious tatami rest area is fitted with massage chairs, and the on-site restaurant serves dishes made with local river fish, making it easy to linger and unwind after a soak.
The facility is open from 10:30 to 21:00 and closed on Tuesdays, though it stays open if a holiday falls on a Tuesday, closing the following Wednesday instead. Admission is an affordable 1,000 yen for adults and 500 yen for children, and free on-site parking makes a visit by car straightforward. Reaching the onsen by public transport requires a reservation-only demand taxi from JR Kururi Line's Kazusa-Kameyama Station, so a little planning is needed for those without a car. Since the heart-shaped light at Nomizo Falls is best seen in the early morning, many visitors pair a sunrise visit to the falls with a relaxing soak here afterward.
Quality
Sodium - Bicarbonate Spring
Emerge
Natural Emergence
Supply
Natural Source Flow
Heat
Heated
pH
pH 8.6
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 1000JPY/Child 500JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 10:30 - 21:00 | ◯ | × | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
2. Irori no Yado Shichirigawa Onsen (いろりの宿 七里川温泉) — Kimitsu City
Tucked deep in the Boso Hills at the headwaters of the Obitsu River sits a solitary inn, Irori no Yado Shichirigawa Onsen. The hot spring source was first opened in June 1984, and in July 1995 innkeeper Mamoru Suzuki began running it as a lodge. What began as a pension-style building became known for an irori (sunken hearth) installed in a meeting room, which proved so popular that the inn eventually built a custom, oversized hearth to meet demand. Suzuki has also helped maintain the surrounding hiking trails for visitors, and the inn remains closely tied to the local Kiwadahata community in Kimitsu City while earning a reputation as one of Chiba's finest hidden hot springs.
The inn's pride is its simple sulfur spring, a rarity in Chiba Prefecture, with a pH of 7.9. The water carries a faint sulfur aroma and a silky, smooth texture. Because the source emerges at a cool 15°C, close to the threshold of a cold mineral spring, it is heated before reaching the baths — yet the official website states plainly that the hot spring water is entirely gensen kake-nagashi (drawn straight from the source), continuously replenished rather than recirculated. The water is said to ease rheumatism, neuralgia, bruises, and gynecological complaints, and its gentle touch has won a loyal following among hot spring enthusiasts.
The bathhouse offers two indoor baths and three open-air baths, alternated between men and women. The undisputed highlight, though, is the inn's oversized custom-built hearth at the center of the building, where guests grill their own seafood, dried fish, Boso pork miso, wild boar, and more than 40 other items over the coals. Guests may even bring their own ingredients to cook for a small charcoal fee, making the time spent around the hearth as memorable as the bath itself.
Day-trip bathing is available from 8:00 a.m. to 10:00 p.m. (last entry 9:00 p.m.), priced at 1,150 yen for adults and 500 yen for children; the inn closes on the first and third Wednesday of each month, so it's worth checking ahead. Overnight guests stay in one of five Japanese-style rooms, with rates starting at 13,900 yen per person including two meals. About 30 minutes by car from Kisarazu-Higashi IC, the inn is surrounded by the scenic valley of the Obitsu River's headwaters, especially beautiful during fresh spring greenery and autumn foliage. Visitors can spend the day fishing or walking the valley trails before settling in for an evening around the hearth.
Quality
Simple Sulfur Spring
Supply
Natural Source Flow
Heat
Heated
pH
pH 7.9
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip OK
Fee
Adult 1150JPY/Child 500JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 08:00 - 22:00 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
Book your stay
3. Benten Kousen (弁天鉱泉) — Minamiboso City
In 1180, after his defeat at the Battle of Ishibashiyama, Minamoto no Yoritomo is said to have fled by boat across the sea from Kanagawa and landed in Awa Province, in what is now Minamiboso City. According to legend, when he purified his hands in a pond near this spot, a manifestation of the goddess Benzaiten appeared to him, and he built a shrine here to mark his renewed resolve. Benten Kousen takes its name from this Itsukushima Shrine dedicated to Benzaiten. The inn is believed to have opened in the 1960s and moved to its present site in 1969, and it continues to operate on a small scale today, welcoming only four groups of guests per day.
The inn's greatest attraction is its ever-changing source water. Officially, the water is described as having three base colors, milky white, pale green, and jade, shifting through intermediate tones over the course of the day, a phenomenon rare enough to be featured in the Nikkei newspaper. The source itself emerges at a cool 14.2°C, classifying it as a cold mineral spring, and is warmed to around 42.4°C for the indoor bath. It is a sulfur spring of the hydrogen sulfide type, containing sulfur, hydrogen sulfide, and boric acid, with a distinctive sulfurous scent. Rather than recirculating the water, the inn drains and refills the bath daily with fresh source water using an overflow method, a practice believed to contribute to the shifting hues.
There is a single open-air bath, used by men and women on a time-rotation schedule, with sweeping views over Tokyo Bay and, on clear days, Mount Fuji beyond the water. The inn has just 11 guest rooms, including some with private open-air baths, and meals are prepared by the innkeeper couple using fresh seafood sourced locally in southern Boso.
Day-trip bathing is available from 10:00 to 15:00, booked in one-hour private slots that must be reserved in advance. Admission is 2,000 yen for adults (bathing tax extra), with bathing-only entry free for middle school students and younger. The inn is about 20 minutes by car from Kyonan-Tomiyama IC on the Tateyama Expressway, or about 10 minutes by taxi from JR Iwai Station on the Uchibo Line. Visitors hoping to see the full range of color changes may want to time multiple short visits throughout the day. Since only four groups are accepted per day, early reservations are recommended for both day-trip and overnight stays.
Quality
Sulfur Spring (Hydrogen Sulfide Type)
Temp
14.2℃ to 42.4℃
Supply
Natural Source Flow
Heat
Heated
Use
Stay OK/Day Trip OK
Fee
Adult 2000JPY/Child ---JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 10:00 - 15:00 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
4. Kameyama Onsen Hotel (亀山温泉ホテル) — Kimitsu City
Kameyama Onsen Hotel sits on the shore of Lake Kameyama, near the geographic center of the Boso Peninsula in Chiba Prefecture. Remarkably, its hot spring was not the result of a deliberate search for onsen water — it was discovered by accident in 1930 during a natural gas drilling operation. The spring served the local community for decades until 1972, when construction of the Kameyama Dam submerged the original source beneath the newly formed lake. A new well was drilled at the current site the following year, and the hotel has drawn its water from it ever since.
The spring is classified as a sodium chloride-bicarbonate spring with a pH of 8.7, placing it in the mildly alkaline range. Water flows naturally from a depth of 2,000 meters at a rate of more than 600 liters per minute, rising to the surface entirely on its own without any pumping. What strikes visitors most is its color: humic substances, formed as ancient plant matter decomposed deep underground over vast stretches of time, dissolve into the water and stain it a deep chocolate brown — so dark that a bather's own body disappears from view just below the surface. On the skin, the water leaves a smooth, almost silky sensation, a hallmark of the moor-type springs prized across Japan for their moisturizing qualities.
The hotel's bathing facilities include separate large baths for men and women, plus a collection of private open-air baths, each with its own character. Most notable is an unheated pool in the men's bath filled directly with spring water at its natural 26.4°C — a rare chance to experience the onsen exactly as it emerges from the ground, without any adjustment. The in-house restaurant serves kaiseki-style dinners built around seasonal Boso ingredients, a fitting way to unwind after a soak.
Day-trip bathing costs 1,000 yen for adults and 800 yen for children, with hours from 11:30 a.m. to 6:00 p.m. (best to confirm current hours before visiting). Parking is free for 50 vehicles and includes EV charging stations. The hotel is about a 12-minute walk from Kazusa-Kameyama Station on the JR Kururi Line, though trains run infrequently, so checking the timetable in advance is recommended. The surrounding area, including Lake Kameyama and Kameyama Dam, offers scenery that changes with the seasons and draws especially large crowds during the autumn foliage season — making this a spot where visitors can combine a soak in dark, mineral-rich water with the natural beauty of the Boso Peninsula.
Quality
Sodium - Chloride - Bicarbonate Spring
Temp
26℃ to 42℃
Emerge
Drilled Self-Flowing
Supply
Partial Natural Flow
Heat
Heated
pH
pH 8.7
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip OK
Fee
Adult 1000JPY/Child 800JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 11:30 - 18:00 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
5. Onjuku no Yu (御宿の湯) — Onjuku Town, Isumi District
Facing the Pacific Ocean, Onjuku in Chiba Prefecture's Isumi District is a seaside town known for its white sand beach and pine groves. Here stands Onjuku no Yu, a day-use bathhouse drawing striking black hot spring water from roughly 800 meters underground. Just a six-minute walk from JR Onjuku Station, it draws not only local residents but also hot spring enthusiasts who travel from farther afield in search of its distinctive water.
What defines Onjuku no Yu above all is the deep black color of its water and its notably thick, viscous texture. Classified as a sodium-bicarbonate spring, hypotonic and weakly alkaline, and categorized as a cold mineral spring, the water carries mineral content accumulated deep underground. As it fills the bath, it takes on a blackish-brown hue, and running it between one's fingers reveals a rich, almost syrupy texture. The facility states on its official website that it serves the spring water without dilution, allowing bathers to experience its distinctive character undiluted, a striking contrast to the light sea breeze outside.
The bathing area includes a spacious main soaking bath alongside functional baths such as a jet-pressure bath and a walking bath, complemented by a Finnish-style sauna and a cold plunge pool. A rest area and lounge are available for relaxing after bathing, giving visitors time to unwind after a long soak. Modest as its quiet seaside exterior may seem, the depth of its full-fledged black-water bathing and sauna facilities is part of what makes Onjuku no Yu special.
Admission is 1,000 yen for adults (700 yen for residents of the Sotobo area) and 300 yen for children. Opening hours shift with the seasons: winter weekdays generally run 16:00-19:00 and weekends/holidays 14:00-19:00, while summer adds an early morning bathing slot and later closing times. The facility is closed every Tuesday (open on national holidays), and Fridays may also be irregularly closed, so visitors should check the official website for the current schedule before heading out. With its easy access from Onjuku Station, it pairs well with a day at the beach or sightseeing along the Sotobo coast.
Quality
Sodium - Bicarbonate Spring
Supply
Natural Source Flow
Use
Stay N/A/Day Trip OK
Fee
Adult 1000JPY/Child 300JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 16:00 - 19:00 | ◯ | × | ◯ | ◯ | ◯ | 14:00-19:00 | 14:00-19:00 | 14:00-19:00 |
6. Shirako Onsen Tokaiso (白子温泉 東海荘) — Shirako Town, Chosei District
Shirako Onsen first emerged in 1989, when a 2,000-meter exploratory well drilled along the gently curving Kujukuri coastline struck a highly saline hot spring flowing up together with natural gas. Though still a young hot spring area, barely four decades old, it now supplies nearly twenty inns along the shoreline. At Shirako Shrine, the town's spiritual center, a legend tells of a white snake coiled atop a white turtle that drifted ashore in 1126 and was enshrined by local villagers as a deity. Ever since, the area has carried a quiet reputation as the 'village of the white snake,' and Tokaiso, drawing its bath water from Shirako Onsen, welcomes travelers into a place where geology and legend sit side by side.
Tokaiso's water is drawn from well No. H-106, a sodium chloride spring with a pH of 7.5 and a source temperature of 28 degrees Celsius. Compared with seawater, it contains less magnesium and far more iodine, a chemical signature unique to Shirako Onsen, with a total mineral content reaching 33,113 mg/kg. The bath fills with amber-to-oolong-tea-colored water, carrying a distinct iodine scent and a salty tang that lingers on the skin. Because the source runs close to body temperature, it is diluted and heated before reaching the tub, then treated with chlorine disinfection and circulation filtration rather than flowing straight from the source. Even without kake-nagashi delivery, the dense salt and iodine content, said to derive from ancient seawater trapped within a natural gas-bearing stratum, offers a character found nowhere else.
The bathing area consists only of separate indoor baths for men and women; there is no open-air bath. The facility is modest in scale but retains the unpretentious atmosphere of a hot spring long cherished by locals. The 33-room inn is known for meals featuring the bounty of the Kujukuri sea, with room-only stays available from 5,500 yen (excluding tax). Just a few minutes' drive from the coast, it also makes a pleasant base for a post-bath stroll along Kujukuri Beach.
Day-trip bathing costs 600 yen for adults and is open from 12:30 to 17:30, though it is not available on Saturdays, and the inn closes entirely from December 30 to January 3, so calling ahead (0475-33-2061) is recommended. The free parking lot holds about 30 cars but can fill up on weekends and during the summer swimming season. By car, it is about three minutes from Shirako IC via the Higashi-Kanto Expressway and Kujukuri Toll Road; by public transport, it is roughly 21 minutes by Kominato Bus from JR Mobara Station on the Sotobo Line to the Shirako-Nakazato bus stop.
Quality
Sodium - Chloride Strong Salt Spring
Emerge
Drilled Self-Flowing
Supply
Circulation System
Heat
Heated
pH
pH 7.5
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip OK
Fee
Adult 600JPY/Child ---JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 12:30 - 17:30 | ◯ | ◯ | ◯ | ◯ | ◯ | × | ◯ | ◯ |
7. Youroukeikoku Onsen Kiyomoto (養老渓谷温泉 喜代元) — Ichihara City
Tucked into the mountains beside the murmuring Yoro River, Kiyomoto is a single small inn known locally as the "kuroyu no yado," the black-water inn. Its own source spring bubbles up right in front of the entrance, and the inn's own website notes that the water rises continuously without pause just steps from the front door — an unusually intimate relationship between building and source that defines the property. The exact date the spring was first developed is unclear, but the inn has long been part of the Yoro Valley's cluster of therapeutic hot spring lodgings.
The water is a sodium chloride-bicarbonate spring with a pH of 8.2, an alkaline cold mineral spring. The source runs at just 17.8°C with a modest flow of about 12.8 liters per minute, far too cool to bathe in directly, so it is heated before being delivered to the tubs. Rich in iodine, the water takes on a deep, glossy dark hue that gives the bath its "kuroyu" nickname, and its silky texture has long been prized as a beauty bath. Because the inn has not disclosed whether the water is diluted, filtered and recirculated, or chemically treated, it should not be described outright as a pure source-fed flow-through bath.
The bathing facilities include separate indoor baths for men and women, plus a reservable family bath for private use; there is no open-air bath. The interior, finished generously in hinoki cypress, has a warm, intimate feel suited to a small inn of only nine guest rooms. In September 2023, Typhoon No. 13 sent the adjacent Yoro River over its banks, flooding the ground floor — including the kitchen and banquet hall — to a depth of more than 1.7 meters. After extensive repairs, including new tatami, flooring, and retiled baths, Kiyomoto reopened in September 2024, about a year after the disaster.
The indoor baths are open from 15:00 to 18:30 and again from 6:30 to 9:00, while the family bath can be booked on a first-come basis from 18:30 to 23:00 for up to 30 minutes at a time — both for overnight guests only. Since July 2022 the inn has not accepted day-trip bathers and operates exclusively for overnight guests. It is about a 20-minute walk from Youroukeikoku Station on the Kominato Railway, or roughly 25 minutes by car from the Kisarazu interchange on the Ken-O Expressway, making it a convenient base for an autumn-leaf getaway that pairs well with nearby sights such as Awamata Falls.
Quality
Sodium - Chloride - Bicarbonate Spring
Emerge
Natural Emergence
Heat
Heated
pH
pH 8.2
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip N/A
8. Inubosaki Onsen Motoyu Kuroshio-no-yu (犬吠埼温泉 元湯 黒潮の湯), Inubosaki Hotel — Choshi City
Inubosaki is a cape jutting into the Pacific Ocean, famous as one of the earliest spots in Japan to witness the New Year's first sunrise. Perched on the bluff above it, the Inubosaki Hotel drilled 1,300 meters underground in 2000 and successfully struck its own source, Kuroshio-no-yu. Drawn from strata formed in the early Cretaceous period roughly 120 million years ago, the water has long been prized as a rare hot spring resource on the volcano-free Boso Peninsula.
What sets this hot spring apart is not merely its ancient geology, but the fact that the water itself originates from prehistoric seawater, making it a genuine fossil-seawater onsen. A joint research team from the Choshi Geopark and the Chiba Institute of Science carried out radiocarbon (14C) dating on several of Inubosaki Onsen's sources and published the results in a peer-reviewed paper. Although the figures vary slightly by source, all point to an age of roughly 10,000 to 11,000 years, scientifically confirming that seawater from around the end of the last ice age, when the Jomon period was just beginning, remained sealed within the strata until modern drilling reached it. Rich in sodium and chloride ions, the water has a distinctly salty character and is said to leave the skin smooth and well moisturized, earning it the local nickname hadabijin no shioyu, the salt bath for beautiful skin.
The baths center on an observation-deck great bath with sweeping Pacific views and an outdoor bath where guests can feel the sea breeze, taking in the blue ocean by day and the glow of the Inubosaki Lighthouse by night. A sauna is also on site, and the ocean view continues from the lobby and restaurant after bathing. The hotel states that some of its tubs use a free-flowing kakenagashi source-water system, but it does not disclose dilution, heating, or circulation details tub by tub, so it should not be assumed that every bath in the building runs on pure source water.
Day-trip bathing requires no reservation. On weekdays it costs 1,200 yen for adults and 700 yen for children; on weekends and holidays, 1,500 yen and 900 yen (rising to 1,700 yen for adults on peak dates such as Golden Week, Obon, and New Year). Hours vary by day, 15:00-21:00 on Mondays and Tuesdays, 12:00-21:00 Wednesday through Friday, and 9:00-21:00 on weekends and holidays, so it is worth checking the official website before visiting. The hotel is an easy trip from JR Choshi Station via the Choshi Electric Railway to Inubo Station, about a 5-minute walk away, making it simple to combine with sightseeing at Inubosaki Lighthouse and the nearby first-sunrise viewpoints.
Quality
Sodium - Chloride Strong Salt Spring
Supply
Partial Natural Flow
pH
pH 7.8
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip OK
Fee
Adult ---JPY/Child ---JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 12:00 - 21:00 | 15:00-21:00 | 15:00-21:00 | ◯ | ◯ | ◯ | 09:00-21:00 | 09:00-21:00 | 09:00-21:00 |
9. Chikura Onsen Chikurakan (千倉温泉 千倉館) — Minamiboso City
Chikura Onsen Chikurakan is a solitary inn drawing its waters near the southern tip of the Boso Peninsula, in the town of Chikura, Minamiboso City, Chiba Prefecture, facing the Pacific Ocean. According to a story handed down through generations, in 1180, after being defeated by the forces of Oba Kagechika at the Battle of Ishibashiyama, Minamoto no Yoritomo fled to Awa Province to rebuild his strength. Along the way, his beloved horse Hagoromo injured its leg; when the horse stepped into a spring welling up beside the road, it is said to have recovered before long, and Yoritomo rejoiced at the spring's restorative power. It should be noted that this is a legend passed down over the centuries through the inn's own tradition, and no primary historical source from the Kamakura period, such as the Azuma Kagami, has been found to corroborate it. Even so, Chikurakan describes itself as Chiba Prefecture's oldest hot spring, and the sheer span of history behind its waters remains one of the inn's great attractions.
The spring is classified as a sulfur sodium-chloride spring. The inn's official information lists a wide range of purported benefits, including relief from neuralgia, muscle and joint pain, gynecological conditions, fatigue, poor circulation, stiff shoulders, skin ailments, chronic digestive trouble, burns, and rheumatism. One notable detail concerns how the water is used: the men's large bath, Shutsujin no Yu, and the women's large bath, Hagoromo no Yu, are diluted with roughly 50% fresh water, while the smaller baths, including the private open-air baths, use the spring water at full, undiluted strength. In other words, not every bath at Chikurakan can be described as a pure source-fed flow-through bath, and the treatment differs from tub to tub, which is worth understanding before a visit. The pH value, source temperature, and whether the water is heated, recirculated, or chlorinated are not stated in the inn's official materials and remain unconfirmed.
The inn offers separate large baths for men and women, along with two types of private open-air baths available by advance reservation. Located just a minute's walk from the Pacific shoreline, Chikurakan offers the rare experience of soaking in the bath while catching the sea breeze. Overnight guests can also enjoy kaiseki-style dinners built around the bounty of the Boso coast, and the inn's understated yet warm hospitality has earned it a loyal following. Day-trip bathing is available as well, and because the private open-air baths are reserved one party at a time, visitors can soak at their own pace without concern for other guests.
Day-trip bathing in the large baths is available from 12:30 p.m. to 7:00 p.m. (last entry 6:00 p.m.), priced at 1,500 yen for adults and 750 yen for children, tax included. The private open-air baths are available from noon to 2:00 p.m. (last entry 1:00 p.m.) for 3,000 yen per party for a 50-minute session; reservations are recommended for both. A pickup shuttle is available from Chikura Station on the JR Uchibo Line for overnight guests (reservation required). The Boso Peninsula enjoys a mild climate year-round, making it a pleasant destination even in winter, and a visit pairs well with flower-picking excursions or a drive along the coastline. Since some details, such as the number of parking spaces, are not listed on the official website, it is a good idea to call ahead (+81-470-44-3211) to confirm before visiting.
Quality
Sulfur-containing - Sodium - Chloride Spring
Supply
Partial Natural Flow
Use
Stay OK/Day Trip OK
Fee
Adult 1500JPY/Child 750JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 12:30 - 19:00 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
Book your stay
Summary: What to Know Before Exploring Chiba's Hot Springs
Chiba's hot springs fall into four natural groupings: the inland Boso hills, the Minamiboso coast, the Sotobo/Kujukuri shore, and Choshi at the peninsula's eastern tip.
Inland Boso. Nomizo Onsen Senju no Yu, Shichirigawa Onsen, Kameyama Onsen Hotel, and Kiyomoto all sit in the hills of central Boso. Nomizo Onsen Senju no Yu stands right at the entrance to Nomizo Falls and Kameiwa Cave, so a soak pairs naturally with sightseeing. Shichirigawa Onsen and Kameyama Onsen Hotel are both in Kimitsu City, roughly 30-40 minutes apart by car. Kiyomoto sits along the Yoro River in Ichihara City, about a 20-minute walk from Youroukeikoku Station on the Kominato Railway, but since July 2022 it has operated as a stay-only property, so day-trip bathing is not available there. Public transport is limited across this area, making a rental car the practical choice.
Minamiboso Coast. Benten Kousen and Chikura Onsen Chikurakan both sit along the coast of Minamiboso City. Benten Kousen is about 10 minutes by car from Iwai Station on the JR Uchibo Line, while Chikura Onsen Chikurakan offers a reservation-only shuttle from Chikura Station on the same line. Both inns cap the number of parties accepted each day and limit reservation windows for their baths, so booking ahead is effectively mandatory. On a clear day, Benten Kousen's outdoor bath offers a view of Mount Fuji across Tokyo Bay.
Sotobo and Kujukuri. Onjuku no Yu, in Onjuku Town, and Shirako Onsen Tokaiso, in Shirako Town, both sit along the JR Sotobo Line. Onjuku no Yu is about a 6-minute walk from Onjuku Station, making it one of the easier stops on this list for travelers without a car. Shirako Onsen Tokaiso does not accept day-trip bathers on Saturdays, so plan a weekday or Sunday/holiday visit instead. This stretch of coast pairs well with a day of surfing or swimming at Kujukuri Beach.
Choshi. Inubosaki Onsen Motoyu Kuroshio-no-yu, at the Inubosaki Hotel, sits at the easternmost point in the prefecture. From Choshi Station, transfer to the Choshi Electric Railway and get off at Inubo Station, about a 5-minute walk from the hotel. Pairing the visit with Inubosaki Lighthouse, famed as one of the first places in Japan to see the New Year's sunrise, and the Choshi Geopark adds useful context for the fossil seawater beneath the bath.
A few practical points apply across the list. Bathing is generally separated by gender at all nine facilities, and swimwear is not worn in the baths themselves, though policies for any day-use family or private baths vary by inn. As at most Japanese hot springs, visitors with visible tattoos should contact the facility in advance rather than assume entry, since none of these nine publish an explicit tattoo policy online. Reservations are strongly advised at the smaller properties, especially Benten Kousen and Chikura Onsen Chikurakan, and required at Kiyomoto, which has not accepted day-trip guests since 2022. Cash remains the safer default at these small, family-run baths, even as card payment becomes more common elsewhere in Japan. Every facility on this list can technically be reached by public transport, but bus and taxi services in the Boso hills run infrequently, so a rental car is the more realistic way to visit more than one or two in a single day.
The information in this article (admission fees, operating hours, water quality data, etc.) is based on research conducted at the time of writing. Details may have changed or contain errors. Please verify the latest information on each facility's official website or through the local tourism association.
