This 4200-hectare virgin forest – about the only remaining virgin forest in Kansai – is administered by Kyoto University’s Department of Agriculture. There are trailheads above the stone hut at Sarari-tōge pass and at Ashū village at the bottom of the pass; register at the office in Ashū before entering. Trails are typically snowed under between late November and late April. Getting to Ashū requires driving along a narrow, twisty mountain road (from Rte 38, take the turn-off after descending from Sasari-tōge pass).
The most basic walk follows old train tracks along the undammed river Yura-gawa. More involved hikes continue beyond the tracks up the river or up side valleys. If you intend to do serious hiking here, grab a copy of Shobunsha’s Yama-to-Kogen Kitayama map at a Kyoto bookshop.