From the Hachiko exit of Shibuya station, turn right of the big Tsutaya and Starbucks. Then turn left on Inokashira Dori which is between Seibu department stores. Keep walking ahead until you get to the koban (police box) at a Y-intersection. Go to the left of the koban and a bit further ahead you'll see the Quattro Building on your left. Club Quattro is on the 5th floor.