AFURI's yuzu shio (salt and yuzu citrus) ramen is one of the most distinctive bowls in Tokyo — a clear chicken broth infused with the fragrance of yuzu, topped with sliced chicken breast, a half-cured egg, and a sheet of nori. Everything about it is delicate rather than assertive. It is the opposite of tonkotsu in every way.
The original branch in Ebisu is the best (and often has a short queue). Other branches in Harajuku, Roppongi, and elsewhere. Also serves yuzu tsukemen (dipping ramen) if you want to try the same broth in a more concentrated form.