This duo of fast-casual noodle shops is all about Japan’s udon, either in warming soups or just lightly sauced, with simple, mostly classic toppings like a thick slab of fried tofu. Order your noodles, then choose from a bevy of tempura for topping and dipping. The U District location is students galore; the new one in Capitol Hill’s 12th Avenue Arts building has a calmer vibe.