We went to Ajisen for lunch today (the latest addition to Chinatown in Richardson). It's Japanese owned and their ramen is VERY AUTHENTIC (I'm a native).
They cook the noodles right and their Tonkotsu (pork) soup was very good. We finished all the soup :-) $7.95 and up (pricey for ramen)
Just don't order Shoyu(soy sauce) Ramen--there are about 4 shoyu-based flavers. $6.95 and up. It was pretty bad unfortunately (shoyu ramen is my favorite).
They also have yaki udon, donburi(bowls), sushi, bento boxes, etc.