Amamionsen

Right by Nankai Koya Line's Amami Station, in the mountains near the Wakayama border, Amami Onsen was opened in the early 14th-century Nanboku-cho era. It's said travelers headed to Mount Koya once stopped here to soothe their fatigue, calling this water 'paradise bath.' A naturally radioactive spring (25°C), it's said to help chronic gallbladder inflammation, gallstones, neuralgia, and digestive troubles. The onsen is housed at Nantenen, a sukiya-style inn beside the Amami River with a 3,000-tsubo Japanese garden. Its main building was relocated from an annex of Sakai City Ohama's 'Shioyu' bathhouse, designed by Kingo Tatsuno, the celebrated Meiji-era architect behind Osaka's Central Public Hall — and it's now a nationally Registered Tangible Cultural Property.