This is our basic learning method for aikido's first principle and one of the first techniques required for grading: shomen-uchi ikkyo.
The fundamental lesson of ikkyo teaches us how to enter directly into an attack. At its most basic level, the tori (defender) practices getting off the initial line of attack and then returning to it in order to take an attacker's balance.
There are many reference sources for this waza, as well as interpretations as to how it can be adapted to other attacks. The most evident historical application of ikkyo involves tori seizing control of an attacker weilding a katana (Japanese long sword) and attempting to cut a shomen-uchi (strike to the forehead). While this is the origin of the waza, from this fundamental application various armed and unarmed attacks, as well as modern-day adaptations, can be explored.
The most important thing to consider is that ikkyo is not solely a technique for dealing with a frontal attack, but rather it is a method of "piercing" through any attack. The goal is to make a direct connection to uke render them unable to successfully continue their attack.
In this video we break down the steps and timing required to circumvent the initial attack. Beyond the kihonwaza, students learn how to later manipulate the attack line and eventually take uke's center directly from the attack line.
As always, comments and questions are welcomed below.