Aoidake Onsen

Aoidake Onsen lies within Aoidake Nature Park in the Yamanokuchi district of Miyakonojo City, Miyazaki Prefecture, tucked into the Wanitsuka mountains beside the Sakai River gorge. It is one of the few mountain hot springs in Kyushu that can be reached on foot from a railway station, about a 10-minute walk from Aoidake Station on the JR Nippo Line. Long operated by the town as the public rest house known as Aoidake-so, the facility passed into private hands in 2023 and reopened in December 2025 after a full renovation as SPA & LEISURE PARK Aoidake. Aoidake-so is simply the former name of the same building, and the new Thermal Lounge Yurukotto occupies its second floor rather than a separate annex.

The water is a sodium bicarbonate-chloride spring, hypertonic and mildly alkaline, emerging at 40.0 degrees Celsius with a pH of 8.0 and a total mineral content of 10.5 g/kg. It carries 4,503.3 mg/kg of bicarbonate ions and an unusually high 1,044.9 mg/kg of metaboric acid, while calcium and magnesium remain low. The result is a remarkably slippery, lotion-like feel on the skin that the operators market as toromi-yu, or thickened water. Pola Orbis Holdings certified it as a skin-conditioning hot spring, the first such designation in Kyushu. The spring is pumped from the property's own well and the baths combine free-flowing and recirculated supply, with heating and chlorine-based disinfection.

The ground-floor bathing area offers a main pool, a hot pool, a walking bath and a body-temperature pool indoors, plus a rock-built open-air bath overlooking the Sakai River gorge, a sauna and a cold plunge. The second-floor Thermal Lounge Yurukotto adds stone-bed bathing, Korean-style ondol rooms, a library of over 10,000 volumes and a coworking space for an extra fee. Day admission is 700 yen for adults on weekdays, 900 yen on weekends and holidays, from 7:00 to 22:00 with no regular closing day. A ten-room lodging wing called Jikkeian, a campground and an RV park share the same grounds.