Onomichi's famous Temple Walk leads up and down the slopes as it passes the 25 temples (it feels like more).
The road on the spot is very badly marked, the streets often very narrow, you go very quickly past a small temple, without taking note of him. My walking section is not exhaustive or correct, it should only show the approximate route.
But beware! After the hike you definitely can not see any more temples! ;O)