Asarigawa Onsen Ski Resort Mountain

The mountain

毛無山 (Kenashi-yama)

Landform

Kenashi-yama is the worn-down remains of an old volcano, and no longer looks like a cone. The 1953 survey calls it heavily eroded, with no crater left, one of a line of lava uplands with flat tops and steep, stream-cut sides. Its lava caps the ridge just west of the lifts and above them. The runs come down the north-east flank below that cap, over older volcanic ground the survey maps separately. On a map, the name is printed at a 548 m survey point north of the lifts, lower than their top.

Rock

On the current national geology map, andesite and basaltic andesite run from the top of the lifts to the bottom, as lava and the broken rock it threw out. The map dates most of it to the very end of the Miocene or the Pliocene, with a band of older lava of the same kind crossing the middle of the hill at roughly 350 to 480 m. JapowDB measures one face here, turned north-east, with 471 m of vertical under the lifts. Because the rock never changes in kind, it holds no reason for that face to split into others, or for the face to turn north-east. JapowDB has not measured how the pitch changes down that face, so the rock cannot be tied to how steep it is.

From published sources, checked by hand · 2026-09-15

That ground is outside the ski area. It is not patrolled.