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Analyzed in 2020, this is a relatively new spring on the shore of Tara, where the slopes of Mount Tara run down to the Ariake Sea. It emerges as a cool 22.8°C mineral spring; bicarbonate makes up about 80 percent of the anions, while magnesium, calcium and sodium share the cations almost evenly. At just 0.18 g/kg it is soft, almost like fresh water, yet 69.5 mg/kg of metasilicic acid gives it its character as an onsen, a quiet water to sink into while watching the great tides of the Ariake Sea.

On the Dogashima coast of western Izu, famed for sculpted rocks and sea caves, two Nishina sources are blended at the town's distribution station and piped in. Calcium makes up about 70 percent of the cations and sodium about 30, while sulfate exceeds 90 percent of the anions: a classic Izu gypsum-type sulfate spring. Alkaline at pH 8.8 yet moderately rich at 2.290 g/kg, the 52.4°C water wraps a body chilled by Suruga Bay breezes, an honest water to sink into as the sea turns gold at sunset.

Shima Onsen is said to take its name from healing "forty thousand ailments," and this water blends two naturally flowing sources from its Yamaguchi district in a mixing tank. Sodium (about 59 percent) and calcium (about 38 percent) lead the cations, while chloride (64 percent) and sulfate (30 percent) dominate the anions. It pairs the warmth of salt with the moist softness of sulfate, clear and easy-going at a gentle 1.42 g/kg, a quietly embracing water beside the Shima River gorge.

This spring sits high in Kankaiji, one of Beppu's eight hot spring districts, and blends two sources through a mixing valve: the Sugi-2 well and a source at the Minamitateishi geothermal power plant, a very Beppu way of using the earth's heat for both power and bathing. Emerging at 91.4°C, its anions are 64 percent chloride and 21 percent sulfate with plenty of carbonate, giving a mildly alkaline water. Clear and faintly salty, its abundant metasilicic acid lends a soft, gentle feel.

Kidachi Onsen Yugashima No. 23 takes its name from a legend that Minamoto no Yoritomo, spotting steam among the rocks while hunting, pried them up with a wooden sword and released the water. Set beside the Kano River in literary Amagi-Yugashima, its calcium and sodium share the cations almost equally while sulfate and bicarbonate balance the anions. Clear, tasteless and odorless, it is a quiet, unassuming water.