Ramen Underground/San Francisco
This was the second place of this SF trip. In an slightly sketchy area that was undergoing a lot of renovation. This was the only place in SF that I went to that looked like the tencho was actually Japanese. There was no lingering like other places, people seemed to know how to eat and get out. Cash only. Very thick deep tonkotsu taste with both chicken and kakuni buta pieces. Lots of weird writing on the walls. I agree with some of the Yelp ratings - I think the place is a bit underrated.
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