What are kumi tachi and kumi jo and why do we practice them? On the surface, they are just kata, exercises in memorization we can test students on. They also teach weapons use, train students’ bodies in movement applicable to aikido, and teach distance and timing.

At a deeper level, there is an internal logic to each one that is more meaningful. Look at kumi tachi number 2, for example. You start standing tip to tip, sword points barely crossing, where both parties are as close as they can safely be. Neither provides an opening. Then one person takes the initiative. In this case, by taking his sword off line. This makes him more vulnerable, so he steps back at the same time. So, the attacker has an opening, a suki. But to exploit it the attacker has to move forwards. If he does this slowly, the other person can move back just as slowly, maintaining ma ai. So the attacker has to leap forwards too fast for his opponent to move backwards. However, the defender has time to respond, because of the distance, and he can respond in a number of ways.

He can return to the status quo ante by stepping back and cutting shomen to reconnect to the attacker’s sword. He can do this so strongly that he overcommits, attacking the attacker back, providing another suki which the attacker can exploit (KT 1). He can step in and to the side, avoiding the blow and stealing the energy to use it to strike at the attacker’s neck (KT 2). He can step back and deflect the attacker’s sword with an upward block (KT 3). He can counterstrike early enough that he takes the initiative back (KT 4). Or he can do something totally different (other KT, variations, etc).

To make this believable, the two partners need to each play their part, but if they are doing things correctly, this isn’t difficult. Each partner should make his partner’s next move feel inevitable. I want beginners to move a lot, to practice safely. More advanced students can work closer together. This increases the realism and benefit, but is more dangerous. These are, after all, lethal weapons we are using.

In the initial position, both partners should imagine a duel in medieval Japan, two samurai trying to kill each other, both intent, looking for the slightest loss of focus to exploit to kill the other guy. One guy provides an opening. It has to be realistic enough that the other guy sees it as a credible chance to kill the other. Too obvious, and the bait won’t be taken. When the bait is taken, the defender must move in just the right way at just the right time. Too soon, and the attacker can adjust. Too late, and the attacker wins.

The attacker must give a credible attack. Not difficult working with a beginner, of course, but the attack has to be better for a more advanced student. Of course, we don’t really want to kill each other, and want to keep a reserve in case our partner totally messes up, but there has to be a credible threat to make the kata work, rather than us just going through the motions (which is perfectly fine while learning the moves but is eventually limiting). Aikido is the “way of harmony and spirit”, after all. There has to be spirit (ki) to harmonise with. And we have to harmonise with it, or there is no aikido.

There are some things common in all the kumi tachi. In particular, as I have been illustrating, controlling the initiative (sente) through suki, position and distance. There are different “messages” in each of the different kumi tachi. These are the main ones I see: KT 1 – don’t over-commit. KT 2 – timing. KT 3 – don’t repeat anything three times in a row. KT 4 – again, timing, and in particular early timing (sen sen no sen) to crush the attacker. KT 5 – don’t let your attacker encroach.

So next time you practice kumi tachi, think on these points.