The Old Temple Loop is the walk that makes Onomichi more than a pretty port. The route links 25 temples over about 2.5 km, climbing and dropping through stone steps, residential alleys, cemetery paths, and small pockets of shade.
You do not need to treat it as a checklist. Jodoji, Saikokuji, Tenneiji, and Senkoji are the obvious anchors, but the pleasure is the movement between them: tiled roofs below, laundry on balconies, cats on warm walls, and the sea appearing between houses.