Yunoshima Onsen

Yunoshima Onsen is a village-run day-use hot spring bathhouse in the Tomiyama district of Toyone Village, Kitashitara District, Aichi Prefecture, tucked into the mountains along the shore of Lake Sakuma. Surrounded by forested peaks and the reservoir created by the Sakuma Dam, it is often described as a "hidden hot spring of Oku-Mikawa," developed and maintained by the local Tomiyama community as part of regional revitalization tied to the dam's construction.

The spring water is classified as a sodium bicarbonate-chloride spring (hypotonic, weakly alkaline, low-temperature spring). Because the source temperature is low, the water is heated before use. The indoor bath is heated, recirculated, and filtered, and disinfectant is used, while the outdoor bath combines a spout of raw source water with a spout of heated water, making the facility's overall water system a partial-flow (ichibu kakenagashi) style rather than a pure flow-through. The spring is said to help with neuralgia, muscle pain, poor circulation, and general fatigue recovery.

The bathing area consists of a rustic, rock-lined indoor bath and a small open-air bath enclosed by a bamboo fence, both sized for only a handful of bathers at a time. The facility is open only on Saturdays, Sundays, and public holidays from 1:00 PM to 7:00 PM, and closed on weekdays. Admission is 440 yen for adults and 330 yen for elementary school children, with preschoolers free (as confirmed in July 2026; subject to change). The outdoor bath is typically closed in winter (roughly mid-November through late April) to protect the facility, leaving only the indoor bath in operation.