Jigoro Kano investigated and preserved the basic principles of the old styles of jujitsu into judo kata. Kenji Tomiki devoted his life to the research and practice of budo and used Jigoro Kano's ideas (judo principles) with his own original idea of competitive aikido as a starting point.
Instead of pursuing the narrow budo principles of aikido, judo, kendo, karate, etc. individually, Tomiki investigated the basic principles common to all budo. Jigoro Kano said that because the only aim in jujitsu was to win in battle this did not fit in with the trend at the time of the Meiji restoration. He said that judo is a way of training and disciplining oneself based on the principles derived from his research. These judo principles are:
1. Principle of natural posture (concerning stance)
Being able to adopt the correct offensive or defensive stance freely to adapt to any attack.
In any match, fast initial movement is essential. Judo has as its essence the principles of old ju-jitsu so that you are in a posture from which you can immediately move and adapt to an opponent's unrestricted attacks. This is a 'posture without a posture' also known as shizentai (natural posture) which applies to both standing and kneeling.
History tells us that jujitsu separated from Samurai Sumo and developed as an original fighting style a long time ago. The first basic skill necessary is correct posture (standing or kneeling) together with quick movement. In particular, this means basic practice of tsugi ashi and shikko (walking on the knees).
i) 8 directions of movement. Basic tai sabaki (body handling).
ii) Forward and reverse turns in the standing and the kneeling position.
2. Principle of gentleness (from a defensive standpoint)
Not resisting an opponent's offensive ability but rendering it useless by body movement.
There are two cases in which you render an opponent's attack powerless by yielding rather than opposing the attack.
i) Flowing with the opponent's power in a grappling situation.
ii) To parry an opponent's strikes, punches, kicks or attacks with a weapon when there is distance between you and your opponent.
The principles of the two cases above are the same. However, in the second case you must practise the basic skills of metsuke (visual focus), maai (correct distance), tegatana (correct use of the handblade), etc.
Unarmed jujitsu was popular from the early days of the Edo period. To defend well against an opponent's unrestricted attacks quick tai sabaki is the greatest asset. The principle of gentleness is the most important foundation of judo.
3) The principle of breaking balance (from an offensive standpoint)
Disrupting an opponent's balance and following close to his body to create the chance of winning.
This is the principle of a weaker power defending against a stronger power. Research into breaking an opponent's balance is important before applying techniques. It is possible to break the balance of a standing person in 8 directions. It is particularly easy to break balance perpendicular to the line connecting the feet. So, breaking an opponent's balance is achieved through a large, quick and powerful body movement rather than by pushing or pulling with muscular strength.
When someone has their balance broken in a forward direction they will react to try to regain their balance making it easy to break their balance in the backward direction and vice versa.
There are two situations for creating an opportunity to break an opponent's balance:
1. Grasping an opponent's sleeves or lapels in a grappling situation.
2. Making contact with or holding an opponent's chin, elbow, wrist, etc.
Jigoro Kano preserved a 21 technique kata from Kitoryu jujitsu as the Koshiki no Kata in Kodokan judo because they represented the most essential principles. This kata clearly presents the judo principles of natural posture, gentleness and breaking balance. By practising this kata you will be able to understand the true nature of judo.
There are no throws that use the feet or hips in the Koshiki no Kata. Indeed there are even a few holds and strikes. However, as a whole it demonstrates movement while in a natural posture, rhythm, distribution of power, etc. which are the things that must be learned.
Rather than teaching his own method Jigoro Kano taught fundamental principles that anyone can use and which will never disappear.
"If the techniques that Jigoro Kano taught don't match these principles then they are not his true teachings but a mistake in his application." (The True Meaning of Judo and the Aim of Training).
In other words, it is nothing but a fundamental expression of the scientific mind and the universal truth derived from it. We can say that the work the Kenji Tomiki Shihan did towards creating competitive aikido used and was supported by these ideas.