Once up on the slopes there are great day hikes to various surrounding peaks, through forests, and along streams with waterfalls. The cloud was low on the hillside when we were there but apparently on clear days there are killer views of Tokyo and its environs.
We thoroughly recommend the area to anyone visiting Tokyo for a while, who may want to escape the concrete and lights. It's easily accessible, within 2 hours from the centre of the city using the local JR line rail service. Well worth the effort.