It's rare that I actually want ramen, but when I do I go to a specific shop. Kamukura is a well-known chain and it happens to sell vegetarian ramen. It's one of the rare places that doesn't use animal products in the broth itself so unless there's meat added afterward it'll be bonafide vegetarian ramen. The side of fried gyoza is a nice touch. The noodes and gyoza can be had for under ￥1000.