Private Sauna Villa in Gunma | THE FOREST SAUNA in the Kitakaruizawa Highlands

THE FOREST SAUNA is a private one-villa rental tucked into the forests of Tsumagoi Village (Kitakaruizawa area), Gunma Prefecture. Up to 5 guests. The sauna, water bath, and outdoor rest deck are entirely yours—no shared spaces, at any hour. Stargaze at midnight or rest with the dawn birdsong; the rhythm of the day is yours to set.

The sauna is a Finnish HARVIA barrel sauna. Heat circulates evenly through the round wooden chamber, and you control the steam and humidity through self-löyly. Through the open window, you watch the forest while you warm up—something you simply cannot do indoors. Up to 4 adults at a time.

The water bath sits on the wooden deck, filled with natural mountain spring water. Soft on the skin, open to the sky, exactly the kind of cooldown the body craves after a long round in the heat.

Infinity chairs on the deck make outdoor rest effortless—forest breeze, dappled sunlight, and the sounds of the woods. It's the part guests talk about most.

For sauna technique and the "totonoi" cycle, see our Barrel Sauna Guide.

Kitakaruizawa & Tsumagoi sit on the northern foothills of Mt. Asama, at 650–1,300m elevation. The seasons arrive early up here: foliage and snow both reach the forest ahead of the city.

Early autumn (September): the last heat fades and mornings turn cold. The gap between the sauna and the air outside sharpens, and outdoor rest gets markedly better. This is the last stretch to enjoy the deck water bath in full.

Foliage (October): the Karuizawa and Kitakaruizawa area typically peaks from mid to late October. Warm up watching a forest turning red, cool off in natural mountain water, then look up at the color from an infinity chair—the richest scenery of the year.

Early winter (November): past the foliage peak, winter closes in. From November through April the deck water bath is closed against freezing; the indoor bath serves as the cold plunge instead. Late November can bring first snow and icy roads—come on studless tires.

Winter (December–February): snow everywhere. In a silent, snow-covered forest, the first step out of the sauna is something no other season can match. The colder it gets, the deeper the calm.

For detailed autumn tips, see our Autumn Sauna Villa Guide. Other seasons: winter / spring / summer.

A 59㎡ whole-villa rental for up to 5 guests. Living/dining/kitchen + bedroom, suitable for groups and families.

Key facilities: HARVIA barrel sauna / Natural water bath (deck) / Infinity chairs / 80-inch projector / Full kitchen (IH, fridge, microwave, rice cooker) / Washer / Wi-Fi / Heating / BBQ grill with charcoal (free).

Amenities: Bath & face towels / Toothbrush / Shampoo, conditioner, body soap / Hair dryer.

From autumn onward, mornings and evenings are cold and outdoor rest chills you quickly—bring a down jacket or fleece. BBQ ingredients, your preferred coffee, and seasonings should be brought separately.

For full facility details, see the Barrel Sauna Villa Stay Guide.

Mainly accessed by car. From Tokyo: Kan-Etsu → Joshinetsu Expressway → Usui-Karuizawa IC → Route 146 for ~60 minutes (about 2.5 hours total from Tokyo Station).

Train + taxi: Karuizawa Station → Naka-Karuizawa → taxi (40 min), or Manza-Kazawaguchi Station → taxi (20 min).

Regular tires fine May–October; studless tires required Nov–April. See the Access Guide for details.

Booking is via Airbnb. Rates vary by season and party size—please check the Airbnb calendar for availability. Facility details are on the villa page.