A vital fundamental move. Irimi from what I understand is a Japanese word meaning to enter the realm of an opponent, it's a universal language of all martial arts, a move in order to initiate an attack and/or counter attack technique, entering while exiting to the back of your opponent to safely move away and form a defensive stance or run away goodbye!...
Remember the best way to self defense is to avoid conflict. when cornered is the best way to apply your skill in the art!