Yoro Valley Onsenkyo Tenryuso

Tenryuso is a seven-room Japanese inn in Yoro Keikoku, small enough for the valley and the household scale to shape the stay. Built in the 1960s, it retains a plain Showa appearance rather than a redesigned boutique finish.

The large communal bath holds Yoro’s distinctive black mineral water, a sodium bicarbonate and chloride spring with iodine. The source begins cool and is heated for bathing; its dark colour and smooth texture give the otherwise simple bath a memorable identity.

Dinner uses seasonal ingredients from the Boso interior, prepared carefully in a traditional Japanese style. Tenryuso suits travellers who want a quiet tatami room, unusual black water and a small country inn after walking the valley. The pleasure is intimate and elemental, without a long list of facilities.