Tekki (Naihanchi) in karate: a sideways kata on one line, differences between Shotokan and Shorin, and an honest learning path with a teacher.
The honest answer: "Tekki" is not a single kata but the name of a family of sideways-walked forms, and which version you learn depends on your style and your teacher. In Shotokan it is called Tekki (Funakoshi renamed Naihanchi; the name is translated as "iron horse"), in Shorin lines Naihanchi [1]; Wado and Shito lines also use the name Naihanchi (practice, ask your teacher). There are three modern forms, Shodan, Nidan and Sandan; whether Nidan and Sandan were created by Anko Itosu or the kata was originally one form is disputed among researchers [1].
What links the family: the stance is a straddle stance, either naihanchi-dachi (shoulder-width, toes slightly inward) or kiba-dachi, and the path (embusen) is a straight line to left and right through the dojo [1]. So you stand wide throughout the kata and move sideways. That makes it an honest test of your leg strength and hip control.
The style question matters. The WKF kata rules state explicitly that kata names vary in spelling, that the same kata can be called differently in different styles and that in exceptional cases an identical name can even denote a different kata. Slight variations as taught by the competitor's style are permitted [2]. We therefore give you no movement sequence here, because any sequence from memory would be wrong for some style.
How long does it take? You often learn the sequence of a kata within a few weeks; quality (stance, tension, rhythm) takes months to years. That is experience, not a study. In Shorin and Matsubayashi lines, Naihanchi Shodan is taught as the first brown-belt (2nd kyu) kata [1]; in other styles it sits elsewhere.
Ask your teacher: is our form called Tekki or Naihanchi? Which of the three? How does it open (only Shodan has a formal opening according to the source [1])? Milestone: you can explain the variant and the specifics of your style in two sentences.
You practise kiba-dachi or naihanchi-dachi with a stable trunk. The pelvis stays neutral, the knees point over the feet, not inwards. Rotations of a few degrees (which produces the "hachi-monji" stance) you learn from your teacher [1]. Milestone: you hold the stance for 60 seconds without wobbling and without the knees collapsing inwards.
You walk the line without technique, just steps and head turns. Gaze and hip lead, the body follows. Milestone: you can walk the line there and back without leaving the path.
Under supervision you learn sections your teacher sets and assemble them slowly. A study with 20 judoka found that five minutes of watching in addition to practice improved performance in a kata [3]. That is a transfer from judo, not evidence for tekki. Milestone: one section runs calmly and in rhythm.
You run the kata in one piece and ask about the meaning of the movements (bunkai). Competition karate judges the kata against the official WKF list and style variants [2]. Milestone: you run the kata without errors, without stalling, and can explain two movements.
This guide explains and motivates; it does not replace supervised training or a coach.
Run the kata once with your mouth closed, breathing through the nose only. If you stay calm, you have distributed tension correctly. If you run out of breath, you have too much force in the wrong muscles. That is experience, not a study.
As a rule yes: Shotokan says tekki, Shorin lines say naihanchi [1]. Versions can differ in details because each style maintains its own school [2].
Three modern forms: shodan, nidan and sandan [1]. Whether they were originally one kata is disputed among researchers [1].
That depends on the style. In Shorin and Matsubayashi lines naihanchi shodan is taught as the first brown-belt kata [1]. Other styles place it differently.
As a supplement yes, as a replacement no. Videos show one school; details such as stance and rotation differ [2]. Learn the kata from a teacher of your style.
The kata's path is a straight line to left and right [1]. The training targets stance, hip and technique at close range; your teacher explains the exact application.
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