Hikite in Karate is the "pulling" of your hand back to your hip into a ready position. This technique is completed at the same time of any strike.
With every punch we throw in Karate Kihon, Kata or Karate Kumite, we pull our free hand back to a ready position. While this is done for a few reasons, the main one is to create the hip twist as this will whip your attacking hand out for the punch. But it's not only used for this, it could be a grab to pull your opponent in onto the punch. It could be used as a parry for an incoming attack. Every movement is done for a reason, not just to look good.
Think if an opponent comes in with a body punch, a parry to this and a grab to the wrist, the grab isn't important as your follow up punch is already started as these two movements are completed at the same time, so instead of trying to execute a block, then a punch, this is more a reactive parry than anything, as we have done this for so long, it should happen naturally if you incorporate this into your basic training drills.
If this can be done as a grab, great, think of two cars crashing head on to each other at the same speed, now think if one of the cars is parked and stationary, the first crash will generate more force, so more damage, the same with this technique, if you can pull an opponent onto your punch, increasing their speed a little it will cause more damage. This is body dynamics, how a body will react to the situation, if your can alter these dynamics, even slightly, it will improve your technique.
- Red Dragons Karate UK Sensei Nathan Foster - Added 4/15/15