Ajiro Onsen

Seaside city on the Izu Peninsula, an hour from Tokyo by Shinkansen. Coastal sodium chloride springs; fireworks over Sagami Bay in summer.

Coastal Izu resort with a long Edo-period bathing history. Famous for the wooden Tokaikan inn, sodium chloride springs, and fresh sashimi at the morning market.

Quiet Kanagawa onsen in the foothills of the Hakone outer rim, on the Manyōshū-era list of historic baths. Plum blossoms in February.

A hot-spring town on the central Izu plain, joining the ancient Kona spring — named in the Azuma Kagami and tied to the Hōjō clan — with Meiji-era Nagaoka. Gentle alkaline "beauty water," Mt. Katsuragi's Fuji-and-Suruga-Bay views, and the Genji history of nearby Hirugakojima.