Accessible from July to September, Gas-san (1984m) is the highest of Dewa Sanzan's sacred mountains. From Hachigōme (八合目; eighth station) the route passes through an alpine plateau to Kyūgōme (九合目; ninth station) in 1¾ hours, then grinds uphill for another 1¼ hours to the top.
From here the pilgrimage route presses on towards the steep descent to Yudono-san. This takes another three hours or so, and you'll have to carefully descend rusty ladders chained to the cliffs and pick your way down through a slippery stream bed at the end of the trail.