Tennen-Onsen Choseinoyu Hot Spring

A day-use bath set back from the Shirahama seafront with a hill behind it, built inside the frame of an early Showa timber warehouse: stone underfoot, Kishu cedar on the walls, ceilings high enough that it reads like an old cure bathhouse (tojiba, 湯治場). Three tubs, all kakenagashi straight from the source. The indoor one, an open-air bath ringed by cherry and maple that regulars call the Momiji-buro (モミジ風呂), and a third with Kishu binchotan (備長炭) charcoal packed across the whole floor of the tub, which rounds the water off and is the one most people come for. The water is a weakly alkaline sodium bicarbonate chloride spring that leaves skin slippery, piped from two springs the owners hold themselves: the hotter Chosei source in winter, the cooler Higashitani one in summer. The ground it stands on was once Koga-yu (古賀湯), which ran dry and shut in the Showa years; Chosei-no-yu opened on the same spot decades later. There is a free footbath by the entrance, a spout you can drink from, and a Wakayama ramen shop on the same lot.