Travelers who jump on the Bullet Train from Tokyo to Nagano prefecture to check in at the famed Hoshinoya Karuizawa resort could spend their weekends hiking on Asamayama, a nearby volcano, or exploring Karuizawa, a local mountain town. They don't. Instead, they dip their bits in thermal spring water and take naps. As an attendant at the spa hotel puts it, the guests "don't like to be so active."
Karuizawa is a popular resort town only an hour from Tokyo that, thanks to its altitude, provides city slickers with a cool escape from the megalopolis's angry summers. Hoshinoya is the escape within that escape, a place away from the crowds.
Hoshinoya presents itself as a middle ground between an onsen, or hot-spring-centric facility, and a western hotel. Where many Japanese inns, or ryokans, force visitors into a regimented schedule, Hoshinoya provides its clients with freedom, an English-speaking staff, and constant access to the springs.
The alkaline baths at Hoshinoya are the real draw. The guest-only Meditation Bath is a windowless cavern. Visitors prepare themselves for immersion in semi-private stalls nearby, then shuffle through streams of water pouring from overhead as they enter the main bath. The room lights are kept low. Experienced bathers sink up to their necks and let the hot spring water wash over them before sloshing down a dimly lit tunnel into a pitch-black chamber nearby.
Adjacent to Hoshinoya is Tombonoyu, a rotenburo, or outdoor hot spring open to the public. It's popular with visitors to Karuizawa, but is only open to Hoshinoya guests until 10 a.m. The baths abut a hillside so visitors watch mountain creatures as they float on, braving drizzles and, occasionally, flurries. The contrast of the steamy bath and the cool precipitation is a gift from the mountain deities.
Back inside, the floors of the cottages nestled into the slopes are heated by thermal water coursing through a complex series of pipes. The feel of warm wood on bare feet is complemented perfectly by the cool mountain breezes that sweep through the ceiling windows.
The few guests that manage to overcome onseninertia and leave Hoshinoya stretch their legs in Picchio, a non-profit wildlife reserve full of Giant Flying Squirrels. The squirrels take off from their nests almost exactly 30 minutes after sunset, so encounters can be almost guaranteed. Still, every visitor has to determine what sort of spectacle is worth his or her emerging from the hot springs. For many, the answer will be none.
More information: A shuttle picks Hoshinoya guest up at the train station and ferries them to a welcome hut where live music and a sweet rice drink serve as a prelude to a soak.