I have tried "oyster ramen" in Kushiro and it was amazing. I lost the picture so I cannot show you, but there were about 10 or 15 pieces of oyster as toppings! The soup was simple and the color was clear. You can see the pictures at this review site.
This ramen shop is in the famous Washo Ichiba (fish market) near Kushiro station. If you have a chance to visit Kushiro, please try this ramen!
Maybe you go to SAPPORO,you can see namy ramen resutaurant. You can eat sapporo-ramen there.Sapporo-ramen is based on miso soup.
If you will go to HAKODATE,you can eat hakodate-ramen,too. Faimous hakodate-ramen is based on salts soup.
Both are delicios.