The Hokuto in Shimbashi (it is a chain) is a decent place less than a minute's walk from the west exit of Shimbashi station. There were several girls in white uniforms behind the counter - the long counter, the stools, sort of it feel a bit like a diner. This ramen shop has entrances at both ends and opens up onto two streets, the sign and door look like the picture regardless of what side you come from. Just go in and sit down, don't wait to be seated. There's no ticket machine, take our bill and pay at the register when you leave. I had what appeared to be the house specialty, the goma tofu dan-dan men - the noodles were plain, but the broth was quite good - it was a dan dan style broth with a very light pinkish color, there was some ground meat in the broth and then some slightly spicy miso on top. The broth wasn't really that spicy for dan-dan men. The bowl was a decent portion and the service was extremely fast.
Amasan review page
Diddlefinger Map (English labels)