Hondani Onsenkan, located in Kawanouchi, Saijo City, Ehime Prefecture, is a historic hot spring counted among the Three Great Hot Springs of Iyo, alongside Dogo Onsen in Matsuyama and Nibukawa Onsen in Imabari. According to the Nihon Shoki, in 639 CE the 34th Emperor Jomei visited the Iyo hot spring with his empress (later Empress Saimei), giving the spring more than 1,300 years of recorded history. Tucked into a quiet mountain valley along the upper reaches of the Daimyojin River, about 5 km southwest of Iyo-Miyoshi Station, the inn offers seasonal scenic beauty year-round. On April 9, 2026, the facility was renovated under the Sanfuku Group as SPA P SPO Hondani Onsen, gaining a karaoke room, Finnish-style sauna, and a campground. The water is classified as a hypotonic alkaline cold mineral spring with a source temperature of approximately 19 degrees Celsius, requiring heating for bathing. The colorless, odorless water has a soft, smooth feel and is cherished as a beautifying bijin-no-yu spring. Therapeutic indications include neuralgia, muscle pain, joint pain, frozen shoulder, chronic digestive disorders, cold sensitivity, fatigue recovery, chronic skin conditions, and chronic gynecological ailments. The facility consists of a main building with an indoor bath and private family bath, plus a new wing housing an indoor bath, open-air bath, sauna, and cold-water bath. After the renovation, day-trip admission is 700 yen for adults and 350 yen for children, with a family bath available for 3,000 yen per 90 minutes. Hours are 10:00 to 22:00 (last entry 21:30), open year-round. Free parking for approximately 50 vehicles is provided. The onsen is about a 10-minute drive from JR Saijo Station and about 15 minutes from Saijo IC on the Matsuyama Expressway.