Kusatsu Onsen Nishiyama Hotel

Kusatsu Onsen is considered one of Japan's finest hot spring resorts, and Nishiyama Hotel stands within this celebrated volcanic spa town in Gunma Prefecture, whose strongly acidic sulphurous waters have a pH as low as 2.1, among the most potent thermal waters in the country. The high hydrogen sulfide and sulfuric acid content of Kusatsu's thermal waters is renowned for its bactericidal properties, skin-clearing effects, and stimulating action on the circulatory system, drawing visitors for therapeutic immersion for over a millennium. A stay at Nishiyama Hotel places guests at the heart of Kusatsu's yumomi tradition, where wooden paddles are used to cool the water while preserving its mineral integrity—a cultural ritual unique to this iconic Japanese spa resort.