Kazawa Onsen Koyokan is a member inn of the Japan Secret Hot Springs Association, built at a historic therapeutic bathing site dating from the Kamakura period in Tsumagoi Village, Agatsuma District, Gunma Prefecture. Founded in 1869 (Meiji 2), this long-established inn is also known for its connection to 'Yukiyama Sanka' (Snow Mountain Hymn).

The hot spring is a magnesium/sodium-bicarbonate spring with source temperature of 44.8°C and pH 6.8. As a pure hot spring with natural flow, no added water, no filtration, and flow-through, you can enjoy the source water as is without any water addition or heating. Effective for neuralgia, muscle pain, joint pain, sensitivity to cold, and fatigue recovery.

With 20 rooms total, there are main and old buildings. Accommodation rates are from 14,040 yen per night with two meals in main building, from 12,960 yen in old building, from 8,640 yen with breakfast, from 7,344 yen room only. Day-use bathing available for adults 500 yen, hours 10:00-16:00. Check-in 15:00, check-out 10:00, open year-round.

Access by car from JR Agatsuma Line Manza-Kazawa-guchi Station (about 25 min). By car, about 70 min from Usui-Karuizawa IC on Joshinetsu Expressway. Free parking available. Inn where you can enjoy history from Kamakura period and pure source flow-through hot spring.