Naihanchi (ナイハンチ) (or Naifanchi (ナイファンチ), Tekki (鉄騎)) is a karate Kata, performed in straddle stance (naihanchi-dachi (ナイハンチ立ち) / kiba-dachi (騎馬立ち)). It translates to 'internal divided conflict'. The form makes use of in-fighting techniques (i.e. tai sabaki (whole body movement)) and grappling. In Shorin-Ryu and Matsubayashi-ryū Naihanchi Shodan is the first Ni Kyu (Brown Belt Kata) although it is taught to Yon Kyu (Green Belts) occasionally before Evaluations for the Ni Kyu rank. It is also the first Shorin-ryu and Shindo jinen-ryu kata to start with a technique to the right instead of the left. There are three modern kata derived from this (Shodan, Nidan and Sandan). Some researchers believe Nidan and Sandan were created by Anko Itosu, but others believe that it was originally one kata broken into three separate parts (probably due to constraints of space). The fact that only Naihanchi/Tekki Shodan has a formal opening suggests the kata was split.
Whilst the kata is linear, moving side to side, the techniques can be applied against attackers at any angle. The side to side movements in a low stance build up the necessary balance and strength for fast footwork and body shifting. The kata are intricate strategies of attacking and defensive movement, done in the kiba dachi, for the purpose of conditioning the legs to develop explosive power. If one rotates one's torso a few degrees to one side or the other while performing Naihanchi/Tekki, the result is the Hachi-monji, or figure eight stance. Some researchers believe the form is a non-ballistic two-man grappling exercise.
In his 1922 book titled To-te: Ryūkyū Kenpō / 唐手 琉球拳法 Gichin Funakoshi called this series of forms "Naihanchi/ナイハンチ" and attributes the form to what he calls the "Shōrei-Ryu/昭霊流." Similarly, Motobu Chōki spells the name of this form "Naihanchi/ナイハンチ" in his 1926 Okinawa Kenpō To-te Jutsu/沖縄拳法唐手術. By 1936, in his Karate-do Kyohan/空手道教範 Funakoshi had started referring to this form as “Kibadachi (騎馬立/キバ ダチ)” or “Cavalry Horse Stance,” while still referencing the original “Naihanchi / ナイハンチ” name. In the 1973 "Karate-do Kyohan The Master Text", a translation of the 1956 second edition of the Kyohan book, there is no longer any mention of Naihanchi and the book claims the form, which it calls "Tekki" is named in reference to "the distinctive feature of these kata, their horse-riding (kiba-dachi) stance." Other than the "Shorei-Ryu" reference, none of these books attribute the form to any particular source or practitioner.