Sandan-kyo Valley

You can get there by bus. The details are here on this website. 

http://visithiroshima.net/plan_your_trip/tour_plans/sandankyo.html

And you probably shouldn’t go in December as the bathrooms are closed, and the maintenance on the pathways aren’t done in the winter so there may be fallen trees, rocks, etc. blocking your way. Plus, it’s an area where it snows a lot. Why not go in the middle of November when the leaves are turning color?