Why are we starting with the left foot in unsoku-ho and tandoku undo tegatana dosa? This article will cover some teaching aspects for beginners, although advanced practitioners can also benefit by understanding “the why”.
Natural left rotation including our solar system
Every planet in our solar system except for Venus and Uranus rotates counter-clockwise as seen from above the North Pole; that is to say, from west to east.
Also, we know track-and-field events including indoor bicycle racing, is set in the counter-clockwise direction.
In the past, almost everybody travelled on the left side of the road because that was the most sensible option for feudal, violent societies. Since most people are right-handed, swordsmen preferred to keep to the left in order to have their right arm nearer to an opponent and their scabbard further from him. Moreover, it reduced the chance of the scabbard (worn on the left) hitting other people.
Furthermore, a right-handed person finds it easier to mount a horse from the left side of the horse, and it would be very difficult to do otherwise if wearing a sword (which would be worn on the left). It is safer to mount and dismount towards the side of the road, rather than in the middle of traffic, so if one mounts on the left, then the horse should be ridden on the left side of the road.
(https://www.worldstandards.eu/cars/driving-on-the-left/)
Unsoku and tandoku undo
The first step of unsoku-ho is to move straight forward with the left foot, this is the direction which is often used in a confrontation. On the other hand being able to move forward quickly is not an easy movement thus it requires a lot of training even if we are used to step forward in daily life. The Achilles tendon plays an important role in stabilizing the posture during walking or running. And we all know “shisei” or correct posture is important.
Turning the body left as the first movement would be much easier and better for beginners with their introduction to footwork. Try and feel the difference between stepping forward with the left foot or turning and stepping with the left foot. Most people will feel more comfortable when turning and stepping, because keeping the balance or seichusen is more easy. If you lean sideways you will feel there is little support or resistance by the leg muscles to slow your move. You can feel that the Achilles tendon does not stop the fall to the side. The use of yōbu will facilitate the sideways movement.
In the early era of Tomiki Aikido, turning and stepping to left (and right) was included in the basic training.
From Kenji Tomiki’s “Introduction to Goshinjutsu” (護身術入門), published in 1974.
Senta Yamada, student of Kenji Tomiki and Morihei Ueshiba performing soto mawashi to the left around 1958.
The foot: a shape for natural shifting
Our foot is designed to be longer than its width. You may feel it is so natural that you do not think about it twice. The shin bone is positioned not in the center but rather towards the back or the heel. This design makes the body better balanced with the body forward. In other words, you can keep your balance pretty well even if someone would push you from behind. However, if someone pushes you from the front, you tend to lose your balance much easier. The same thing can be said when the pressure comes from either the left or right side. Shifting to a side may not be a wise or a desirable move from a martial art perspective, it is, however, a useful training method for a beginner to learn how to shift smoothly and swiftly to the side without turning. Keeping the hip-joint and the knee flexible is required to do a step to the side without turning
Easier to make a hanmi (半身) position
It is easy to step and turn to the left, as mentioned previously. It is a good method to introduce “hanmi” to a beginner while turning and stepping to the left, it will feel more natural. The angle of both feet is about 60°.
Left posture hanmi will be used as a strategy when your opponent is attacking with the right hand (armed or unarmed). You can easily entering the blind side.
Left turning and/or stepping in other martial arts
Iaido first level (shoden), turning to the left and cut is a basic movement.
Karate kata for beginners, heian shodan start to the left
And in Ballroom dancing : The Waltz
“Man in right posture, step to the left with left foot……” Man is Tori (taking the initiative) and Woman is Uke.
Study Group Tomiki Aikido 