Experience beautiful skin and health at an Onsen with a thousand years of history, and savor a once-in-a-lifetime moment with seafood tea kaiseki.

Ikoanaso, a Property in Izu Nagaoka Onsen offering private medicinal stone open-air baths and seafood tea kaiseki. The Onsen at Ikoanaso, with a history of a thousand years, features a medicinal stone radon bath utilizing abundant "Bad Gastein stones." Renowned as a beauty-enhancing bath, it is highly praised. Enjoy the synergistic effects of free-flowing Onsen and natural radium for both physical and mental well-being. In rooms with medicinal stone open-air baths and private medicinal stone open-air baths, you can relax in a private setting without worrying about others. Meals feature luxurious seafood tea kaiseki. Savor the exquisite seafood-based tea kaiseki cuisine, a once-in-a-lifetime culinary experience. The rooms are purely Japanese-style, offering a serene atmosphere. All the medicinal stone open-air baths and indoor baths in the rooms use natural Onsen water. Enjoy a relaxing stay in Izu Nagaoka.

  • I stayed one night in a detached Room.Although the Ryokan is located in a quiet town rather than an Onsen resort area, once I stepped inside, I had the strange feeling of being at a Ryokan surrounded by nature deep in the mountains.Since the Room had an open-air bath, I didn’t use the public bath or private baths, and other than going to the dining area, I stayed in my Room and relaxed the whole time.The open-air bath was a bit difficult to adjust to the right temperature at times, but it was wonderful to be able to soak alone for as long as I liked.Because the dining area consists of fully private rooms, I was able to enjoy my meals calmly, which was great. Every dish was carefully prepared, there were many courses, and everything was delicious—I was very satisfied. The staff member who served our meals also seemed very dedicated and left a good impression.Since I stayed in my Room throughout my stay and meals were also in a private room, I hardly encountered other guests. Listening to birdsong while looking out at the garden, I was able to spend a relaxing and meaningful time.Thank you very much for taking care of me.

    Yahoo!トラベルユー... 3/7/2026
  • We arrived a little early, but our Room was already ready, so we were shown in without having to wait. The gentleman at reception was very pleasant, and the first impression of the Accommodation was excellent. The woman who guided us to our Room was cheerful and energetic.It was a spacious Room with two large beds, a sofa, a table, a tatami area with a low table and floor chairs, a shower room, an open-air Onsen bath, a small courtyard garden, and two TVs that also had BS channels—very exciting. The floor chairs were especially comfortable.There were two private open-air baths (one large and one small). The larger one was a roofed rock bath; the smaller felt ideal for two people. Both had washing areas. The water had a silky texture and warmed us thoroughly. The private open-air baths were outstanding—definitely not to be missed. The open-air bath in the Room is filled with Onsen water yourself; at first it seemed like it might be a bit of work, but adjusting it to the perfect temperature on our own turned out to be enjoyable.We chose the standard meal course, so it wasn’t particularly extravagant or flashy, but everything was carefully prepared, delicious, and just the right amount.We were satisfied with everything—the Room, Onsen baths, meals, and service. We’d love to visit again in another season. Next time I might even enjoy strolling around in yukata as well.

    Yahoo!トラベルユー... 3/2/2026

Facilities and Services

See All
  • Hot spring
  • Room with Open-Air Bath
Open-air bath / Free-flowing hot spring / Large public bath / Private bath
IN14:00~24:00
OUT10:00
Number of rooms13 rooms
PetNot allowed
Your childPermitted

【No Meal Plan】Day-use Onsen is not enough! ~Unlimited free private baths~

IN 14:00~22:00
OUT 10:00
¥19,360
No meals ; 2 peopleTax included¥17,430
(USD 109.79)

【New Easy Plan】1 Night with Breakfast ~ Unlimited Free Private Bath ~

IN 14:00~22:00
OUT 10:00
¥23,716
Breakfast included ; 2 peopleTax included¥21,346
(USD 134.45)

【No Meal Plan】Day-use Onsen is not enough! ~Unlimited free private baths~

IN 14:00~22:00
OUT 10:00
¥19,360
No meals ; 2 peopleTax included¥17,430
(USD 109.79)

【New Easy Plan】1 Night with Breakfast ~ Unlimited Free Private Bath ~

IN 14:00~22:00
OUT 10:00
¥23,716
Breakfast included ; 2 peopleTax included¥21,346
(USD 134.45)

【No Meal Plan】Day-use Onsen is not enough! ~Unlimited free private baths~

IN 14:00~22:00
OUT 10:00
¥20,570
No meals ; 2 peopleTax included¥18,520
(USD 116.65)

【New Easy Plan】1 Night with Breakfast ~ Unlimited Free Private Bath ~

IN 14:00~22:00
OUT 10:00
¥24,926
Breakfast included ; 2 peopleTax included¥22,436
(USD 141.32)

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Rooms With Open-Air Baths Popular At Stays

Accommodation With No Meals Included

Relaxing Japanese-Style Accommodation

Gourmet Stays

Stays Popular For Spectacular View

Pregnancy-Friendly Accommodation

Introduction of the Accommodation

Open-air bath

The Onsen of Ikona-so with a thousand years of history

The Onsen at Ikona-so features a therapeutic radon bath utilizing an abundance of "Bad Gastein mineral stones." Known as a beauty-enhancing bath, it has received high praise for its ability to improve skin texture. These stones, sourced from the globally renowned Austrian spa town of Bad Gastein's healing tunnels (Heilstollen), are combined with the natural hot spring qualities of Izu Nagaoka, allowing guests to enjoy the soothing warmth of natural radium within the bath. The water flowing from the spout is entirely non-recirculated, offering a pure, free-flowing therapeutic radon Onsen experience. All baths, including the large public bath, private open-air baths, in-room open-air baths, and indoor baths, are 100% natural hot spring water sourced directly from the spring. The spring quality is a simple alkaline spring, which is expected to provide benefits for conditions such as neuralgia, muscle fatigue, frozen shoulder, and weak digestion.

Original Bed

Original Bed

"Beauty and health stem from high-quality sleep." At Ikonaso, we provide exclusive beds featuring original urethane and pocket coil designs. Dustless pillows and comforters made with endless fiber are also available. Experience this superior sleeping comfort. *Beds are only available in Japanese-Western style rooms ("Asahi" and "Yuzuki").

Facilities and Equipment of Accommodation

  • The room
    The room
  • Hot Springs & Baths
    Hot Springs & Baths
  • Facilities & Services
    Facilities & Services
  • Meal
    Meal

Basic Information

Card information
VISA / MASTER / JCB / AMEX / DINERS
Pets
Not allowed
Breakfast【Breakfast】Dining Area
Your child
You can stay.
Room service
Not available
Common amenities
  • ○ Shampoo · conditioner
  • ○ Body soap · soap
  • ○ Towel · Bath towel
  • ○ Body towel · sponge
  • ○ Toothbrush set
  • ○ Comb · Brush
  • ○ Shower cap
  • ○ Hair dryer
  • ○ Shaving
  • × Shaving Gel/Foam
  • × Bath additives
  • ○ Yukata
  • × Nightwear
  • × Bathrobe
  • ○ Slippers
  • ○ facial cleanser
  • ○ Toner
  • ○ Lotion
  • ○ Makeup remover
  • ○ Cotton swab
  • × Cotton
  • × Clothing deodorizing spray
  • ○ Refrigerator
  • × Minibar
  • ○ Electric kettle
  • ○ Tea set (free)
  • ○ Television
  • ○ Safe
  • × Scale
  • × Trouser press
  • × Free morning edition
  • × Pay-per-view broadcast
  • ○ Satellite broadcasting
  • × Video on Demand
  • × Radio
  • × CD player
  • ○ DVD player
  • × Blu-ray player
  • × Speakers for portable audio
  • × In-room PCs and tablets
Facilities and Features
  • ○ Hot spring
  • ○ Rooms with open-air baths available
  • ○ Open-air bath
  • ○ Free-flowing hot spring
  • ○ Large public bath
  • ○ Private bath
  • × Sauna
  • × Ganbanyoku (rock bathing)
  • × Within a 5-minute walk from the station
  • × Within a 5-minute walk to the convenience store.
  • × Indoor pool
  • × Outdoor pool
  • × Pet-friendly
  • × Spa facility
  • × Fitness
  • × Free shuttle service
  • × Shuttle Service (Paid)
  • × Room service
  • × Room Service Available 24 Hours
  • × Barrier-free
  • × Childcare services
Esthetic Massage
None
Fitness gym
None
Public Bath
The number of Public Bath
2
Business Hours
06:00~24:00
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring
Remarks
Cleaning is conducted from midnight to 6:00 AM.
Open-air bath
The number of Open-air bath
2
Business Hours
06:00~24:00
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring
Remarks
Cleaning is conducted from midnight to 6:00 AM.
Private bath
The number of Private bath
2
Business Hours
06:00~24:00
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring
Remarks
Cleaning is conducted from midnight to 6:00 AM.
Room with Open-Air Bath
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring
Remarks
Room with Onsen Indoor Bath
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring
Remarks
Spring quality and benefits

Mildly alkaline simple hot spring

Bruises / Muscle Pain / Sensitivity to Cold

※Regarding the notation of "Gensen Kakenagashi"
In some facilities, heating or adding water for temperature adjustment may be performed. Additionally, please note that in some parts of the facility, the hot spring water may not be free-flowing from the source. For more details, please contact each facility.

SaunaNone
Hot stone spaNone
Others【Other Accepted Cards】 UC, DC, NICOS

Reviews

Overall Score
4.62
Wonderful (19)
  • Rooms & Amenities
    4.68
  • Facility
    4.32
  • Hospitality & Service
    4.74
  • Meals
    4.53
  • Onsen & Bath
    4.89
  • Satisfaction
    4.58

*Reviews that have been translated from Japanese.*

*Showing only reviews from 一休.com (Japanese) and Yahoo!トラベル.*

Access Information

Address
Shizuoka Prefecture243-3 Kona, Izunokuni City, Shizuoka Prefecture
TEL:+81-55-948-0868

Transfer at Mishima Station on the Tokaido Shinkansen to the Izu Hakone Railway and get off at Izu-Nagaoka Station.
Take the Izu Odoriko train from Tokyo Station and get off at Izu-Nagaoka Station.
From Izu-Nagaoka Station, take a bus for 5 minutes and get off at "Sogo Kaikan Axis Katsuragi-mae," which is a 0-minute walk.

Parking Information
Fee
Free for guests
Parking time
---
Parking space
No restrictions
Number of parking spaces
13 cars available outdoor
Valet service
Unavailable
No Reservation Required

Pickup and drop-off information
Unavailable

Frequently Asked Questions

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