Take the South-east exit of Shinjuku station, walk along Koushuu kaidou (The big road. You'll see Tower Records on the left of it and Newoman on the right) until you reach Meiji-dori. Turn right (you should see a Yoshinoya on the corner) and walk along Meiji-dori. Antiknock is on the left hand side in the basement of the Ray Flat building.