I had a chance to go to Onomichi for an afternoon to hang out with a friend, and we made our way to Tsutafuji ramen, which ranks very high on the ramen blogs and was also a recommendation from a relative who lived in Onomichi. Tsutafuji was recognizable from a few blocks away since it was the only place with a line out the door.
The shop is a single counter with about 14 seats. You order either a large or a small, and you can choose some extra toppings if you like, but that about it for the menu.
From what I can gather, Onomichi ramen is a shoyu based soup made with a meat stock (chicken and/or pork) with a fish stock (I'm not sure what the fish base is made from). There's also a good amount of pork fat added to the bowl for extra richness.
This was a very good bowl of ramen. All the parts of the ramen worked together to create a good flavor balance. I especially liked the broth. It wasn't overly salty, and provided a good balance of flavors. While it doesn't hit you over the head with bursts of flavors, it was possible to identify all the flavors at work. In this sense, it was prototypical ramen with some local character.
I should note that the other places that came recommended in Onomichi are Shukaen (朱華園) and Ichibankan (壱番館). I would have tried these places if I didn't find myself enjoying the walks along the steep slopes and around the temples. It's very San Francisco-esque there.