Nakamoto is very popular for its super hot ramen. This video introduces the hottest ramen called "Hokkyokuten (North Pole)". There're also normal menu so don't worry. It is said that only several people had succeeded at eating up Hokkyokuten.
"Mouko Tanmen Nakamoto - Meguro"
2-13-45 Kami Osaki, Shinagawa-ku, Tokyo
There are other 4 Nakamoto branch in Tokyo area. The original shop is in Kami Itabashi, Itabashi-ku, Tokyo.