Nigorikawa Onsen Shineikan

Shineikan stands in the Nigorikawa caldera, a volcanic basin in the northwestern part of Mori Town in southern Hokkaido. Founded in 1900, it is one of a handful of small bathhouses scattered across the basin, and it has been run alongside a working farm for generations. The Nigorikawa hot springs themselves are far older: a statue of Yakushi Nyorai dedicated in 1798 still survives locally, and the springs were formally opened in 1807. Each bathhouse in the basin draws on its own separate source, so Shineikan is a distinct establishment from neighbouring day-use baths such as Motoyu Shinsenkan Nikori-no-yu.

Mori Town's official tourism information lists the water under the old classification as a boric-acid-bearing, earth-type saline spring, which corresponds to a sodium chloride spring in the modern system. The only analysis posted in the changing room dates from the 1930s, and no current-format certificate is available, so published figures for pH and source temperature differ between sources. The water is a pale yellow-brown carrying fine mineral flakes, with a distinctive scent suggesting iron and petroleum. It is served straight from the source with no reheating, no recirculating filtration and no chlorination, and decades of deposits have built up in thick crusts around the tubs and across the floor.

The bathhouse in the old wing is mixed-gender and holds three tubs of differing sizes hewn to look as though cut from rock, with water temperatures ranging from roughly 42 to 46 degrees Celsius. A separate indoor bath for women is located in the newer wing. The timber bathing hall was extended repeatedly between the Meiji and Showa eras, and its weathered ceiling and exposed beams are exactly what draws hot spring enthusiasts here. Day-use bathing runs from 8:00 to 20:00 and costs 400 yen for adults and 150 yen for children of elementary school age and under. Parking is available and closures are irregular. Overnight lodging has ended, and the inn now accepts day-use bathers only.