I have been Santouka three times and will add to the overwhelming good opinion of this place.
The service is friendly, fast and efficient. I've had the shio ramen which is apparently the most popular. It's creamy and delicious and the noodles are perfectly cooked. I tried it with the pork jowl once and while it was very good, I found the pork jowl too fatty (although I recognize that's probably the idea). The miso ramen is also very good as are the pork dumplings. Yum!
The only frustrating thing I experienced was the hostess refusing to let us sit down without the other person in our party being there. I get that they are trying to serve as many people as they can the quickest but it put a huge kink in my party's plans.
I walk by Santouka all the time as it's in my area and it has a lineup outside very often. I would suggest everyone try it!