This is one of our brown belt combinations.
1. Driving off the back leg make jodan kizami zuki.
2. Leave the punching arm out and quickly close the distance by shuffling up with the back leg (suri ashi),
3. Drive off that leg and perform gyaku zuki chudan and snap back to fighting stance kamae.
Try and keep the same height throughout the combination and try not to telegraph the attacks. This is a great way to close distance very quickly, whilst at the same time concealing the attacks.
Timing when performed fast should be a quick 1,2.
For our brown belt examination we require 2 sets on each leg slowly and 2 sets on each leg fast.
Kizami Zuki Double Step Gyaku Zuki Video Tutorial