A 100% natural spring hot spring facility located in Matsukawa Valley, selected as one of Japan's top 100 autumn foliage spots. Near Kaminari Falls, the main attraction is the 17-meter-long mixed-gender outdoor bath built utilizing the valley's natural giant rocks. The spring quality is calcium-sodium sulfate-chloride hot spring, known as 'natural lotion' for its skin-beautifying properties. Two sources provide abundant hot water - Source 1 at 65°C with 55L/min, Source 2 at 74°C with 135L/min. Bathers can enjoy the magnificent seasonal views of Matsukawa Valley, especially the autumn foliage, considered the best in the Koshinetsu region. The bath is cleaned for 2 hours daily, ensuring cleanliness. A campground is attached, accommodating family and solo camping. For the mixed bath, women must wear paper underwear (free) or towels/swimsuits, men must wear paper trunks (free) or swimsuits. Free Wi-Fi available and pets are welcome.