鬼サウナ

Oni Sauna sits inside the Hōzuki-no-yu bathing wing of the Noboribetsu Grand Hotel, built around the "oni" (demon) imagery long tied to the nearby Jigokudani valley. The sauna room's rock-faced exterior and a gold, club-shaped stove are meant to evoke a demon's den, while the interior stays wood-lined with a large window and a round side window framing the hotel's garden and waterfall.

The room itself runs hot: an auto-löyly system keeps the sauna near 110°C, with steam released once every hour. Cooling off happens in a pair of cauldron-style outdoor tubs nicknamed for the blue and red oni — a 16°C natural plunge fed by chlorine-treated mountain stream water, and a 43–44°C warm tub for those who want to alternate rather than shock the system. A separate cypress-wood plunge, also 16°C, sits inside the main bathing hall alongside a 95°C dry sauna and 13°C cold bath for a milder option.

Outside, a wood deck faces the hotel's signature waterfall, giving the cooldown area a steady backdrop of falling water and ambient noise rather than a view of a parking lot. The hotel alternates gender access daily — women on odd-numbered days, men on even-numbered days — so the sauna and its surrounding baths aren't open to everyone every day.

As part of a hotel bathing wing, access is set up for day visitors as well as guests, with walk-ins and day passes available at a moderate price point. It's built for adults, and the hours shift slightly depending on the day of the week.