Kasen-An Seni Onsen Iwa no Yu

Nagano Prefecture/Hokushin

Experience true relaxation by doing nothing at our hidden hot spring accommodation, where you can enjoy the beauty of the changing seasons.

A serene Onsen Ryokan, "Kasenen Senjin Onsen Iwa no Yu," nestled in the mountains of Suzaka City, Nagano Prefecture. A mystical place where you can experience the beauty of the changing seasons. The secret to its many repeat visitors lies in the philosophy of hosting travelers while the hosts themselves continue their journey of life, deepening their craft. Every aspect, from cuisine to design to hospitality, cherishes the connections between people. Some things remain unchanged through time, while others evolve with the times—all for the sake of people. Come and rejuvenate your mind and body at this one-of-a-kind, special retreat.

  • My first trip to Karuizawa with my mother! This Accommodation is famous for being hard to book, and we happened to find an available date, so we made a Reservation right away!! We drove there in a rental car, and from the moment we arrived, the staff’s warm hospitality made us feel truly welcome. Everything about the Accommodation was wonderful. There are four private Onsen baths that don’t require a Reservation, as well as a large public bath and a cave bath. Surrounded by trees, it’s an Accommodation where you can feel time passing quietly. I’ve stayed at many Hotels and Ryokans before, but this was the first time I experienced such outstanding hospitality—including the food!! It’s easy to see why so many guests return again and again!

    kohmao 8/17/2026
  • It was a wonderful Accommodation surrounded by greenery. Because we could take our time during meals, we ended up completely full, but it reminded me that this is how dining is meant to be enjoyed. The bath was also incredibly relaxing. The Accommodation itself offers very generous space per guest, creating a true sense of openness, and the beautifully maintained garden trees and the gentle sound of the river were wonderfully soothing. Above all, the staff’s warm, unpretentious hospitality made us want to return in a different season.

    青蜻蛉 8/10/2026

Facilities and Services

See All
  • Hot spring
Open-air bath / Free-flowing hot spring / Large public bath / Private bath / Room service
IN15:00~19:00
OUT12:00
Number of rooms18 rooms
PetNot allowed
Your childPermitted

Introduction of the Accommodation

Ideal land healed by Satoyama
Ideal land healed by Satoyama
Ideal land healed by Satoyama
Ideal land healed by Satoyama
Ideal land healed by Satoyama
Ideal land healed by Satoyama

Our Property is a secluded retreat nestled in the countryside. We welcome you to experience an ideal harmony with nature. Upon arrival, please pass through the gate and proceed forward. As you continue, you will come across a bridge over the Senjin River. Enjoy the journey to our Property as part of your experience.

On-site
On-site
On-site
On-site
On-site
On-site
Well-equipped facilities

The well-equipped public space was created with the desire for you to enjoy encounters with thoughtfully designed areas.

Cave Bath "Sennin no Yu"

Cave Bath 'Sennin no Yu'

"The 'Sennin no Yu,' connected to the men's and women's large baths, is a cave bath extending up to 30 meters. It is a mixed-gender bath, so please wear a bathing suit when using it. With a maximum depth of 1.2 meters, you can enjoy an adventurous experience."

The Four Seasons of Hana Sen-an
The Four Seasons of Hana Sen-an
The Four Seasons of Hana Sen-an
The Four Seasons of Hana Sen-an
The Four Seasons of Hana Sen-an
The Four Seasons of Hana Sen-an
The Four Seasons of Hanaen.

Starting in 1989 as a single property in the mountains. The concept of "a truly relaxing property" remains unchanged, constantly creating new value. Enjoy the changing of the four seasons.

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
Pets
Not allowed
BreakfastThere is no information about breakfast.
Your child
You can stay.
Room service
Available for use
We accept requests until 10:00 PM.
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
15:00~11:00
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring (Heating)
Remarks
The famous cave bath "Sennin no Yu" is a rare natural hot spring where the cave itself serves as a flowing bath, with water streaming through the interior like a river at an impressive rate of 250 liters per minute. The cave, surrounded by natural rock formations and filled with steam, creates an atmosphere akin to a natural mist sauna. The interior of the cave bath is mixed-gender, and guests are kindly requested to wear designated bathing attire. Access to the cave bath is available from separate entrances in both the men's and women's large communal baths.
Open-air bath
The number of Open-air bath
2
Business Hours
15:00~11:00
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring (Heating)
Remarks
Private bath
The number of Private bath
5
Business Hours
15:00~11:00
Hot spring
Available
Free-flowing
Available
Milky hot spring water
None
Additional Information
100% natural hot spring (Heating)
Remarks
There are a total of 5 private baths, each with a unique atmosphere. One of them is exclusively for guests staying at Senzantei. No reservation or additional fees are required. Towels and other amenities are fully provided in the bathrooms.
Room with Onsen Indoor Bath
Hot spring
None
Free-flowing
None
Milky hot spring water
None
Additional Information
Remarks
Spring quality and benefits

Mildly alkaline simple Onsen

Relaxation effects, insomnia, neuralgia, cold sensitivity, fatigue recovery, cuts, abrasions, burns

※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

Reviews

Overall Score
4.89
The best (63)
  • Rooms & Amenities
    4.86
  • Facility
    4.89
  • Hospitality & Service
    4.98
  • Meals
    4.76
  • Onsen & Bath
    4.94
  • Satisfaction
    4.89

*Reviews that have been translated from Japanese.*

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

Access Information

Address
Nagano Prefecture3159 Nirei, Suzaka City
TEL:+81-26-245-2453

Approximately 20 minutes via Route 406 from "Suzaka Nagano Higashi IC" on the Nagano Expressway towards Sugadaira Kogen.

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

Pickup and drop-off information
Unavailable

Frequently Asked Questions

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