Tendo Onsen

Sulfur springs at 880m on Mount Zao. Ski-and-onsen pairing in winter; famous frost-covered 'snow monsters' in late January.

Iconic Taisho-era street of wooden inns lit by gas lamps in the snow. Tucked into a narrow gorge in Yamagata.

Sendai's century-old onsen valley along the Natori River — 'one of Japan's three Imperial Springs' (御湯) and known for its 60m Akiu Otaki waterfall.