The shock of Japan’s first cold plunge bath inside the sauna room. A new frontier where extreme heat and cold intersect.
Aichi Kiyosu City
"Yunoya Natural Hot Spring Yukichiro" is a large natural hot spring facility in Kiyosu, Aichi Prefecture. The 2023 renovation introduced the "Zero-Second Sauna Room," an astonishing setup with a cold plunge bath installed inside the sauna room, offering a one-of-a-kind experience that lets you move from intense heat to instant cooling in a single step. It also features a high-temperature sauna exceeding 100°C and baths using excellent natural hot spring water. In the expansive outdoor air bath area, many chairs are arranged, promising blissful rest away from the noise of the city.
TypeNatural Hot Spring
A sodium-calcium chloride hot spring that springs from deep underground. Rich in salt, it is beloved as a "hot water" bath with excellent moisturizing and warming effects. In addition to a spacious open-air bath, you can enjoy natural hot spring water in a wide variety of baths such as carbonated spring baths and pot baths, and the pleasant warmth lingers long after bathing.
Sauna TypeDry Sauna
Stove TypeConvection Stove (Sauna Stone)
Capacity30people
A stadium sauna boasting overwhelming heat that easily exceeds 100°C. Auto löyly activates every 15 minutes, maintaining powerful heat waves and high humidity at all times. Sweating on the top tier is an intensely powerful experience, with heat penetrating deep into the body in a short time, making this a fully authentic sauna room that strong-style sauna enthusiasts will appreciate.
Sauna TypeSteam Sauna
Stove TypeBuilt-in Stove
Capacity18people
A steam sauna where radon, which dissolves easily in water, is carried by steam and absorbed into the body through breathing and the skin. The steam is 100% natural hot spring water.
Water QualityNatural Water (Groundwater, Spring, etc.)
Capacity5people
An extra-cold cold plunge bath installed inside the sauna room, with a temperature around 14°C. Its appeal lies in the indulgent feeling of soaking in water while breathing in the heat, as well as the ultimate convenience of eliminating the need to move elsewhere. Cooling down while watching the sauna theater offers a glimpse of the future of bathing experiences.
Water QualityHot Spring Water
Capacity3people
A gently textured cold plunge bath lavishly using the facility's proud natural mineral hot spring water. The water quality, refined through charcoal filtration, is exceptionally clear, and its defining feature is a refreshing sensation that seems to gently envelop the entire body. It has softness even in its coldness, allowing you to feel the blessings of high-quality natural water on your skin.
Closed Days: None
1110-1 Shimonogawara Shimonokiri, Kiyosu, Aichi Prefecture
Gender Access
Gender Separated
Curated by an expert who visits onsen and sauna facilities every day and has explored 300+ locations — only facilities confirmed to be truly exceptional are featured.
Learn more
The shock of Japan’s first cold plunge bath inside the sauna room. A new frontier where extreme heat and cold intersect.
Aichi Kiyosu City
"Yunoya Natural Hot Spring Yukichiro" is a large natural hot spring facility in Kiyosu, Aichi Prefecture. The 2023 renovation introduced the "Zero-Second Sauna Room," an astonishing setup with a cold plunge bath installed inside the sauna room, offering a one-of-a-kind experience that lets you move from intense heat to instant cooling in a single step. It also features a high-temperature sauna exceeding 100°C and baths using excellent natural hot spring water. In the expansive outdoor air bath area, many chairs are arranged, promising blissful rest away from the noise of the city.
TypeNatural Hot Spring
A sodium-calcium chloride hot spring that springs from deep underground. Rich in salt, it is beloved as a "hot water" bath with excellent moisturizing and warming effects. In addition to a spacious open-air bath, you can enjoy natural hot spring water in a wide variety of baths such as carbonated spring baths and pot baths, and the pleasant warmth lingers long after bathing.
Sauna TypeDry Sauna
Stove TypeConvection Stove (Sauna Stone)
Capacity30people
A stadium sauna boasting overwhelming heat that easily exceeds 100°C. Auto löyly activates every 15 minutes, maintaining powerful heat waves and high humidity at all times. Sweating on the top tier is an intensely powerful experience, with heat penetrating deep into the body in a short time, making this a fully authentic sauna room that strong-style sauna enthusiasts will appreciate.
Sauna TypeSteam Sauna
Stove TypeBuilt-in Stove
Capacity18people
A steam sauna where radon, which dissolves easily in water, is carried by steam and absorbed into the body through breathing and the skin. The steam is 100% natural hot spring water.
Water QualityNatural Water (Groundwater, Spring, etc.)
Capacity5people
An extra-cold cold plunge bath installed inside the sauna room, with a temperature around 14°C. Its appeal lies in the indulgent feeling of soaking in water while breathing in the heat, as well as the ultimate convenience of eliminating the need to move elsewhere. Cooling down while watching the sauna theater offers a glimpse of the future of bathing experiences.
Water QualityHot Spring Water
Capacity3people
A gently textured cold plunge bath lavishly using the facility's proud natural mineral hot spring water. The water quality, refined through charcoal filtration, is exceptionally clear, and its defining feature is a refreshing sensation that seems to gently envelop the entire body. It has softness even in its coldness, allowing you to feel the blessings of high-quality natural water on your skin.
Closed Days: None
1110-1 Shimonogawara Shimonokiri, Kiyosu, Aichi Prefecture
Gender Access
Gender Separated
Curated by an expert who visits onsen and sauna facilities every day and has explored 300+ locations — only facilities confirmed to be truly exceptional are featured.
Learn more