Ninoike-sanso (二ノ池山荘)

Ninoike-sanso is a high-altitude mountain hut beside Nino-ike, Japan’s highest-altitude lake, on Mt. Ontake. It’s a classic summit-zone staging base: you use it to split a long Ontake ascent, time sunrise above the cloud layer, and position yourself close to the crater area for early starts. Because Ontake is an active volcano, route access can change with volcanic alerts—so this is a hut where planning and up-to-date checks matter.