Irimi (trans. entering) is a yang tactic.  In its most simplistic application, when a defender applies irimi, as a yang tactic, the attacker must supply yin energy in order for the defender to enter without clashing.  However, as with all things yang, an element of yin is internally present within irimi as well.  Yin energy allows one to enter with yang energy in such a way to as mimic a river on its way to a great ocean.  Through a mixture of yang and yin, often manifested through linear and curvilinear motion, and/or moments of penetrating and yielding, a defender can enter upon an attacker as a river roars down a mountain seeking the path of least resistance the entire way.  This means that one can employ entering along a spectrum of tactical situations ranging from the simplistic to the sophisticated.  For example, as was mentioned before, a defender can enter by harmonizing one’s yang energy to the attacker’s yin energy.  As another example, a defender can also enter by harmonizing the subtle yin elements contained within the yang nature of irimi with one’s intent to penetrate an attacker’s defenses.  Like a watercourse way seeking the path of least resistance, one can also thus enter yang to yang.  The following video is an example of a drill we use to embody an understanding of these subtle shifts in energy transference as they apply to the tactic of irimi. Training Partner: Michael Harris - Nikyu. (1 minute, 27 seconds)