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Jōmon natural onsen - Shiraku no yu

縄文天然温泉 志楽の湯じょうもんてんねんおんせん こころざしらくのゆ

A Jomon-themed bathhouse over a 1,300-meter fossil-seawater spring

Other
Kanto·Kanagawa

Day Use

Yes
10:00–23:59

The bath opens at 15:00 instead of 10:00 on the 3rd Wednesday of each month (except August) for scheduled maintenance. The bath and changing rooms close at 23:45, 15 minutes before the listed closing time. Additional maintenance closures may be announced separately.

¥1,170

New Year, Golden Week and mid-August Obon dates are charged at the weekend and holiday rate. Rental house wear is 330 yen, a towel set (bath and face towel) is 310 yen, a bath towel alone is 210 yen, and a face towel alone is 150 yen, tax included.

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaYes

Sauna room of any kind

Bathing Arrangements

Mixed BathingNo

Shared bathing area for all genders

Baths are gender-separated (labeled men's and women's) throughout; no mixed bathing mentioned.

Policies & Services

TattooNo

Allows entry with visible tattoos

KidsWith Conditions

Welcomes children and families

Children under 5, and anyone in diapers regardless of age, are not admitted; ages 5+ are admitted at the child rate.

DiningYes

A restaurant or dining room open to visitors, not only meals for overnight guests

WashingYes

Shower, wash stations, soap and shampoo provided

TowelsYes

Towels to rent or borrow at the desk

Rest AreaYes

Relaxation space for after bathing

Listed alongside a tatami lounge (畳語らい処) and a treatment corner (縄文げん氣処) in the facility guide.

ParkingYes

On-site or nearby parking available

Highlights

Steam Sauna
Lukewarm Bath

About

The bathing here is straightforward: an indoor bath and an open-air rotenburo built around andesite boulders brought from Yatsugatake and trees from Kyushu, a men's dry sauna, and a women's mist sauna made to look like a seabed cave. The water rises from over 1,300 meters underground, ancient seawater trapped in the rock. It runs salty and mild rather than hot, easy to sit in for a long soak, and leaves your skin smooth afterward. The building itself has a story. It stands on the site of a former semiconductor factory that shut down in 2002, and the owners rebuilt it around a Jomon (縄文) theme, reusing some of the factory's old timber for the pillars and beams. One tub is a repurposed miso barrel about 120 years old; another, shaped like a magatama (勾玉) bead, is set with red stone from Shinmeikan (新明館), a ryokan at Kurokawa Onsen in Kyushu. A bumpy path patterned after Jomon pottery leads from the washing area to the indoor bath and works the soles of your feet. A soba restaurant on site can be used on its own, and there's a tatami lounge to rest in afterward.

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Ryugo

2 years ago

A wooden, creaky, worn, and dimly lit onsen complex. But that's not a minus — it's just its character, for those who aren't into neon lighting and smooth plastic surfaces. There are two baths: one indoors and one outdoors. Plus a barrel bath. I didn't check the temperature, but it was just right for me (meaning hot water fans might find it too mild). There's a sauna. And a small rest area with onigiri and tatami. If you want a proper dinner, there's a restaurant attached next door (I didn't go myself). There's parking, but I'm not confident it'll have free spots during peak hours. The lack of English pretty much anywhere was a concern, and the Japanese signs are written in a pretty distinctive font, so if your Japanese isn't great, there might be some discomfort. But overall it's a good place.

Onsen Oni

Last updated September 19, 2026