Chiba · Kameyama Onsen (Kimitsu)
Kameyama Onsen Hotel
亀山温泉ホテル
About 70 minutes from central Tokyo via the Aqua-Line, a hot-spring inn founded in 1950 on the shore of Lake Kameyama in the Boso hills. Its chocolate-brown 'kuroyu' bicarbonate water — billed as Boso's finest beauty bath — flows freely into a large bath with lake and forest views. Day use 11:30–18:00, ¥1,000 on weekdays; no day bathing Thursdays and Fridays. In autumn pair it with a foliage cruise on the lake.
- Price (adult)
- ¥1,000
- Hours
- 11:30–18:00 (leave by 18:30)
- Closed
- Thu & Fri (day bathing)
- Access
- 10 min walk from Kazusa-Kameyama Station (JR Kururi Line); 30 min by car from Kisarazu-Higashi IC
- Water type
- Bicarbonate spring
- Tattoos
- Ask ahead
- Admission
- Day bathing: adults ¥1,000 / children ¥800. Towel rental charged. Well stocked: shampoo, treatment, cleanser and peeling gel in the bath, lotions and BB cream in the changing room. The two private semi-open-air baths are for overnight guests first and cost extra. 'Relaxed day plan' with kaiseki lunch and private room from ¥5,000
- Baths
- Two gender-separated bathhouses (the panoramic bath overlooks Lake Kameyama), no rotenburo. An unheated 'source tub' at about 26°C sits beside the heated pool — the chocolate-coloured water is so dark your body disappears at 50 cm. Overnight guests bathe around the clock
- Water
- Sodium chloride-bicarbonate spring (alkaline, hypotonic, cool), flowing naturally at over 600 L/min from 2,000 m down at about 26°C. Humic 'moor' compounds give it a deep chocolate colour and a toasty baking-soda smell; bicarbonate leaves skin silky — billed as 'the finest beauty bath in Boso'. 100% source water, free-flowing (heated)
- Parking & access
- Free parking for 100 cars. About 15 min on foot / 3 min by car from Kazusa-Kameyama Station on the JR Kururi Line (ask about pick-up). About 30 min from Kisarazu-Higashi IC on the Ken-O Expressway via the Aqua-Line, along Route 24 (Kururi Kaido) towards Kamogawa; about 90 min from central Tokyo
- Phone
- 0439-39-2121
- Official site
- kameyamaonsen.jp ↗
- Open in Google Maps
- Google Maps ↗
Essentials
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Why go
- Free-flowing chocolate-brown kuroyu
- Lake Kameyama views
- 70 min from central Tokyo
A chocolate-coloured natural spring — a 14-room inn above Chiba's largest lake
Kameyama Onsen Hotel is a 14-room inn on a rise above Lake Kameyama — Chiba's largest lake, in the centre of the Boso Peninsula — in Kimitsu, and since opening in 1950 it has guarded its own source, which flows naturally at more than 600 litres a minute from 2,000 metres down. The water is a sodium chloride-bicarbonate spring: humic 'moor' matter from ancient vegetation gives it a chocolate colour so deep that your body vanishes at 50 cm, and in morning light it glows like red wine. Bicarbonate softens the skin's surface, leaving you astonishingly smooth — a textbook 'beauty bath' that the inn proudly calls the finest in Boso, and gentle enough that it holds 'Welcome Baby' certification. Both gender-separated bathhouses include an unheated 'source tub' at about 26°C where you can feel the baking-soda slipperiness undiluted, and since the third-generation owner took over in 2018, two crowdfunded private semi-open-air baths overlooking the lake have been added. Day bathing runs 11:30–18:00 (closed Thu/Fri) for ¥1,000. Nothing flashy — but one of the most distinctive springs in Kanto, a place that truly draws guests on the strength of its water alone.
Tips & notes
① Day bathing closes Thursdays and Fridays, with other closure days — check the official site or LINE. Some notices say 16:00 start on Tuesdays, so phone (0439-39-2121) before a morning visit. ② No rotenburo in the main baths — for open air, ask about the private semi-open-air baths (overnight guests first). ③ The 26°C source tub is cool in summer and cold in winter — alternate with the heated pool. ④ The dark water can stain white towels, and you can't see the tub floor — mind the steps. ⑤ The original bath salts and lotion that reproduce the chocolate colour are popular souvenirs. ⑥ Kazusa-Kameyama is the terminus of the Kururi Line with a train every 1–2 hours — a car is the realistic option.
Getting there
About 90 min by car from central Tokyo: Aqua-Line → Kisarazu-Higashi IC on the Ken-O Expressway → Route 24 (Kururi Kaido) towards Kamogawa for 30 min; free parking for 100. By rail, take the Kururi Line (a train every 1–2 hours) from Kisarazu on the JR Uchibo Line to its terminus Kazusa-Kameyama, about an hour, then 15 min on foot (ask about pick-up). Ideal as a stopover on a Boso drive, combined with boating or cycling at Lake Kameyama, Seiwa Roman-no-mori (15 min), Mother Farm (30 min) and Kamogawa Sea World (25 min).
Before you go
- No official tattoo policy is published — ask at reception.
- Ryokan day-use hours are limited and may be suspended in peak season — phone the same morning.
- Last entry is 30–60 minutes before closing.
Features
Mood & scenery
Convenience
Price
Who with
Amenities
✔ Verified operating: 2026-09 Operating status and rates cross-checked against the official site and onsen guides (full source notes in Japanese on the JA page)
Prices and hours change. Check official sources before visiting.
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