Matsunoyama Onsen Ryounkaku is a traditional hot spring inn and member of the Japan Secret Hot Springs Association, located in Matsunoyama Onsen, Tokamachi City, Niigata Prefecture. The main building, a three-story wooden structure built in the early Showa period (1938), is designated as a Registered Tangible Cultural Property of Japan, making it a historically valuable building. It sits atop a small hill, preserving the charm of traditional wooden architecture.

Matsunoyama Onsen is known as one of Japan's 'Three Great Medicinal Hot Springs,' alongside Arima Onsen and Kusatsu Onsen. Legend has it that about 800 years ago, a woodcutter discovered a hot spring where an injured hawk was resting and healing its wounded wings. The source temperature is a high 84°C, and the spring quality is sodium/calcium-chloride spring. The salt content is extremely strong - so much so that salt was extracted during the postwar period - and the water prevents cooling even in winter.

The hot spring water has a pale greenish tint and is popular among hot spring enthusiasts. There's a large communal bath called 'Kagami-no-yu' and a private family bath called 'Taka-no-yu,' both with 100% source water flow-through. The family bath is available free of charge. Due to the high-temperature source, the water is adjusted to an appropriate temperature but still offers a pleasantly hot bath. It's said to be effective for neuralgia, muscle pain, joint pain, sensitivity to cold, chronic skin diseases, and chronic gynecological conditions.

The inn has 17 rooms total, with 3 rooms having bath/toilet and 14 rooms without toilet. It has an elevator, air conditioning/heating, Western-style toilets, and amenities including yukata, towels, and toothbrushes. One wheelchair is available (not fully barrier-free). Seasonal local cuisine is served, with mountain vegetables and mushroom dishes being popular.

Accommodation rates are 14,450-22,150 yen per person per night with two meals (tax included). Day-use bathing is available from 12:00-15:00 (may be unavailable during busy periods) for 800 yen for adults. Check-in is at 15:00, check-out at 10:00, and the inn is open year-round.

Access is by car from Matsudai Station on the Hokuhoku Line (about 20 minutes), with free shuttle service available (1 trip per day at 15:21, reservation required). By car, it's about 40 minutes from Shiozawa-Ishiuchi IC on the Kanetsu Expressway, or about 60 minutes from Toyoda-Iiyama IC on the Joshinetsu Expressway. Free parking is available. It's a historic hot spring inn where you can enjoy traditional wooden architecture and one of Japan's three great medicinal hot springs.