Sometimes a good Tan Tan Ramen is all you crave and Takekuma is there to satisfy. The restaurant is a tad fancier than what I'm used to, but not everywhere serves Tan Tan Ramen, Hot & Sour Ramen, and Tanmen that all taste good. Takekuma fills up fast with Japanese businessmen during the lunch hour so try to get there at exactly 11:30am. And I've heard that they only serve ramen for lunch so if you go for dinner and they don't have it...it ain't my fault.
Take the Tokyo Metro to either Akasaka Station (Chiyoda Line) or Tameike-Sannō Station (Ginza Line, Namboku Line). I don't remember the exact directions from there so I hope the map below helps. It appears easier to get to if you go from Akasaka Station. The actual shop is hidden, but look out for a white sign that says Takekuma. You'll see it hanging in front of the building. Open for lunch from 11:30am to 2:30pm. Open for dinner from 5:30pm to 10:30pm. Closed on Sundays.
Other sites that mention Chinese Restaurant Takekuma: