Nagayu Onsen — Carbonated Hot Spring Soak

Nagayu Onsen (長湯温泉) in Taketa City is one of Japan's few naturally carbonated hot springs (炭酸泉, tansan-sen). The water contains high concentrations of dissolved carbon dioxide, creating tiny bubbles that cling to the skin like champagne — the bubbles improve blood circulation and give a tingling sensation.

The town's signature bathing style is 'long soak' (長湯, nagayu) — the water temperature is only 35–38°C (cooler than typical onsen), allowing hour-long soaks without overheating. The carbonation means even cool water creates warming effects.