Many noodles used in ramen are simply made of wheat, which is a simple carbohydrate. Beans/legumes are a good source of protein (among other things).
If you use real yakisoba noodles that are made from buckwheat flour, it has the advantage of decent fiber and protein (a complete protein, like soy), but not as many vitamins as beans.
If you use real yakisoba noodles that are made from buckwheat flour, it has the advantage of decent fiber and protein (a complete protein, like soy), but not as many vitamins as beans.