In introducing nikyo, it is important to note that the irimi movement used differs from that used in ikkyo. In ikkyo, you turn to the inside of your opponent’s body, bring your body close, and drop your hips as you enter. This movement contains movements similar to those used with a spear.

For nikyo, however, you turn to the outside, and as you enter you raise your hips upward. This action contains movements similar to those used with a sword. Ikkyo and nikyo therefore show opposite types of movement. Many people tend to think that nikyo is about taking the opponent’s arm or wrist in joint-lock and worrying whether it can be made to hurt or not. But from a bujutsu perspective that sort of thing alone has little value. The real value in nikyo is found in the importance of the process of getting into position to apply the joint-lock. Practicing with the sword can help you understand this, particularly in the way it shows how you have already entered from the moment you’ve made contact.

Shoji Nishio Sensei
Yurusu Budo (pg 38)