Chiba · Kujūkuri / Shirako Onsen
Spa & Resort Kujūkuri Taiyō no Sato
スパ＆リゾート九十九里 太陽の里
One of the Bōsō peninsula's largest spa resorts, in Shirako on Kujūkuri Beach. Soak in iodine-rich, tea-coloured Chōsei spring water in the open-air bath, with seven rock-bath rooms, saunas, nap lounges, banquet halls and lodging on site. Open straight through from 10:00 to 08:00 the next morning; stays past 01:00 incur a late surcharge. Free shuttle from JR Mobara Station (reservation required). ¥1,600 weekdays, ¥1,900 weekends. Tattoos—including stickers and paint—are strictly refused.
- Price (adult)
- ¥1,700
- Hours
- 10:00–08:00 next day (no entry 07:00–09:59)
- Closed
- Open daily (one maintenance closure a year)
- Access
- About 20 min by free shuttle from JR Mobara Station (Sotobō Line; reservation required); 25 min by car from Mobara-Chōnan IC
- Water type
- Simple spring
- Tattoos
- Not allowed
- Admission
- Admission (bath and face towels included), entering 10:00–17:00: adults ¥1,700 weekdays / ¥2,000 weekends, holidays and high season; children (3 to elementary) ¥800–1,300. Entry after 17:00 ¥1,500/¥1,800. Early bath 5:00–7:00 entry ¥1,200. Overnight stay 1:00–5:00 +¥1,500. Loungewear ¥200–400. Bedrock spa 'Iori' ¥800
- Baths
- A hot-spring resort on 6,000 tsubo (2 ha). Among many outdoor baths, the all-cypress tub and the rock bath use the resort's own 'Chosei-no-yu' source; plus jets, foot bath, far-infrared and salt saunas. The 500 m² bedrock spa 'Iori' (2014), one of the largest in the prefecture, has seven rooms; manga corner, recliners and nap room; outdoor pool in summer (11 Jul–31 Aug)
- Water
- Sodium bicarbonate-chloride spring (alkaline, hypotonic, cold mineral), pH 8.8, 20 L/min. A blackish-brown 'kuroyu' type moor water — alkaline, smoothing the skin. Diluted, heated and recirculated with filtration
- Parking & access
- Free parking for 300–400 cars. About 15 min by free shuttle from the east exit of Mobara Station on the JR Sotobo Line (phone booking required), or the Kominato bus for Shirako-shako to 'Hitotsumatsu Kaigan', 3 min on foot. About 40 min from Togane IC via the Keiyo Road, Chiba-Higashi JCT and Togane Road, then Route 128
- Phone
- 0475-32-5550
- Official site
- taiyounosato.co.jp ↗
- Open in Google Maps
- Google Maps ↗
Essentials
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Why go
- Open 10:00 to 08:00 next day
- Brown spring water rich in iodine
- A free shuttle runs from Mobara Station
A night on Kujukuri in hot water — a spa resort with black-water rotenburo and a 500 m² bedrock spa, open until 8 a.m.
Spa & Resort Kujukuri Taiyo-no-Sato is an all-in-one hot-spring resort on 6,000 tsubo (about 2 hectares) near Hitotsumatsu beach in Chosei, Chiba — the midpoint of the 66-km Kujukuri shoreline — combining a spa complex with an 82-room hotel wing. Its own source, 'Chosei-no-yu', is a sodium bicarbonate-chloride spring (pH 8.8) of the blackish-brown 'kuroyu' type typical of the Kanto plain — alkaline, and smoothing to the skin. Two outdoor tubs, the all-cypress bath and the rock bath, use this natural water; the rest is a varied line-up of jets, foot bath and far-infrared and salt saunas. The defining feature is the hours: open continuously from 10 a.m. to 8 a.m. the next day, so you can spend the night among the manga corner, recliners and nap room (a ¥1,500 surcharge for staying 1–5 a.m.) and greet dawn in the rotenburo with the Kujukuri sea breeze. The 500 m², seven-room bedrock spa 'Iori' (2014) is among the largest in the prefecture, and an outdoor pool opens in summer (mid-July to end of August), making it a family-friendly 'onsen theme park' for a full day. Admission, towels included, is ¥1,700 on weekdays and ¥2,000 at weekends — popular as the finish to a day of surfing or swimming, or as an hour-and-a-half-from-Tokyo alternative to a hotel night.
Tips & notes
① Pricing has six tiers by entry time, day and season — entering after 17:00 is ¥200 cheaper, early morning 5–7 a.m. is ¥1,200. No entry 7:00–9:59 a.m. ② Staying past 1 a.m. adds ¥1,500; under-18s need a guardian after 22:00. ③ Only two outdoor tubs — cypress and rock — are natural hot-spring water; the rest is heated tap water. ④ Bedrock spa costs ¥800 extra and requires its loungewear. ⑤ The Mobara Station shuttle must be booked by phone (0475-32-5550). ⑥ Very busy in high summer and at weekends; weekday evenings are pleasant. ⑦ Not to be confused with 'Taiyo-no-Sato Inubosaki' in Choshi (now summer-only day bathing).
Getting there
From Tokyo Station, the JR Sotobo Line 'Wakashio' limited express reaches Mobara in about an hour (rapid/local about 1 h 20 min); from the east exit take the free shuttle, about 15 min (phone booking required), or the Kominato bus for Shirako-shako about 15 min to 'Hitotsumatsu Kaigan', 3 min on foot. By car: Keiyo Road → Chiba-Higashi JCT → Chiba-Togane Road, Togane IC → south on Route 128 about 40 min; about 1 h 30 min from central Tokyo; free parking for 300+. Combine with Kujukuri beach, the Shirako hot-spring area and Mobara for a half day or an overnight.
Before you go
- Tattoos are explicitly not allowed, even if covered.
- 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
Sauna & wellness
Who with
Price
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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