Ken Ken Ramen is located at 3378 18th Street, San Francisco, CA, 94110. They are open Tuesday to Saturday from 6 PM to 10 PM and Sundays 12:30 PM to 3:30 PM and 6 PM to 9 PM.
I had their tonkotsu ramen (only served on Tuesdays and Wednesdays) with extra noodles and it was good. Their egg was especially delicious and their broth has a bit of a mushroom taste. I may have eaten too much, but it was worth it.