Matsusakaya Honten Gero Onsen

Matsusakaya Honten in Gero, Gifu prefecture, draws bicarbonate-rich thermal waters from one of Japan's 'three great onsen' — Gero Onsen, Arima Onsen, and Kusatsu Onsen — whose waters are scientifically certified as among Japan's most therapeutically effective, with the Gero bicarbonate spring specifically recognized as a 'bijin-no-yu' (beauty water) for its skin-softening properties from sodium bicarbonate at temperatures around 82°C in the Hida River gorge of the Japanese Alps. Gero's traditional ryokan town spans the Hida River gorge with suspension bridges linking hot spring inns to open-air rotenburo overlooking the racing green river below, and the weekly 'Gero Onsen Fireworks Festival' in summer creates aerial pyrotechnic displays mirrored in the river's thermal steam. The proximity to the UNESCO World Heritage Shirakawa-go and Gokayama thatched farmhouse villages, accessible via mountain road from Gero, connects the thermal tradition to Japan's most celebrated example of traditional mountain community architecture.