Ayu Ramen specializes in well, its namesake, Ayu (鮎, Sweetfish) Ramen (ラーメン, Rāmen), which is an extremely light and clear shio ramen (塩ラーメン, Shio Rāmen, Salt Ramen) served with an entire grilled fresh ayu sitting on top. The dish is so minimalistic, it's almost a work of art. The soup is bright and clear, with their own in-house thin noodles, topped with some sliced negi (葱, Spring Onion), a slice of nori (のり, Seaweed), a bit of herbs, and that beautiful ayu that has been gutted and deboned. The shop itself is also a very much, hole-in-the-wall shop, just with a long queue outside. Consisting of a single set of 8 counter seats by the roadside, this is very much a no-frills, yet homely ramen. The soup is extremely light, yet also deep and delicious at the same time. Before you know it, you'll have downed an entire bowl, and are contemplating if you should get a second round of noodles! That's just how good Ayu Ramen is, and it's why it's built a strong following in ramen guidebooks, and the area!
Do note though, that while the shop is open for lunch and dinner. They only serve Ayu Ramen for dinner, and serve a seasonal ramen for lunch.