Aihanmi katatedori shihonage is one of aikido's most representative throwing techniques. With aihanmi you open both your hand and body. This type of irimi is important because you face your opponent directly, which is particularly characteristic of aikido. By opening in this way, your opponent's attack misses its mark, but you remain in a position to control him. I often see people trying to do this movment simply by shifting their feet and bodies to the side, but this is not a true opening movement, and in fact puts you in range of the opponent's attack.

Aikido training begins with acknowledging your opponent, so it is important to adopt a posture that welcomes him. Of course, at that point you have already begun to control him as well. This is even easier to understand if you learn the sword and jo. The Founder often said: “Aikido does not begin the moment your hand is grabbed; the technique is already over the instant your hand is grabbed.”

Shoji Nishio Sensei
Yurusu Budo (pg 72)