Theoretically, the Afterimage Technique is a move that can be performed (to some degree) in the real world, since it merely requires moving faster than the eye can see. This is a similar phenomenon to that of one moving their hand back and forth very fast, and seeing a sort of afterimage of the hand. However, the speed required to move the entire body is far too much for a normal human to perform.
The image itself cannot perform physical tasks, as it fades through everything. Most often, it is used to dodge an incoming attack and get behind the opponent to perform a counterattack. Its usage is not limited to just counterattacks though, as it can also be used to confuse enemies: the image is used to distract the enemy, thinking it is the actual fighter, giving the user a chance to perform the actual attack. In Tough, Afterimages are characterized as being see-through distortions of the users.