Tosaryu Onsen Sanyoso is a natural hot spring ryokan perched on a hilltop in Usa-cho, Tosa City, Kochi Prefecture, with sweeping views of the Pacific Ocean. Located at the gate of Seiryuji Temple, the 36th of the 88 sacred temples of the Shikoku Pilgrimage, it has long served pilgrims and travelers. Its private source, Tosaryu Onsen, is a sodium-calcium chloride spring (hypertonic, neutral, high-temperature) with a rare 42.5°C source temperature for Kochi. The golden-hued water is known as yu of heat for its excellent heat retention typical of chloride springs. The ryokan offers an open-air bath, large indoor bathhouse, jar baths (tsubo-yu), and a free ocean-view foot bath, all with magnificent Pacific views. Both overnight stays and day-trip bathing are welcomed.