"Kodachijutsu" (swordsmanship of a short sword) is a swordplay style using a wakizashi (the shorter one of the two swords people used to carry on the waist). It is often simply referred to as kodachi.
Although named as kodachijutu, it does not mean an art using a kodachi (small sword).
Since it uses a sword shorter than a uchigatana (a type of long sword), the name was coined by adding "ko" (short) to "tachi" (a sword or swordplay). Kodachijutsu was established in the times when wakizashi was used and therefore, specifically it is an art using a wakizashi.
The dimensions of wooden swords used in training depends on the school and seems to be determined by the sizes of the short swords used at the time each school was established.
(The length of short swords, which had been rather long in the Sengoku period (the period of Warring State), gradually decreased.)
Few swordplay schools specialize only in kodachijutsu, which is usually included as one style of swordplay.
Not all schools, however, use kodachijutsu.
Techniques of kodachijutsu mainly consist of irimi (technique for avoiding an attack by stepping into the dead zone of the attacker) and also includes many techniques like jujutu (Japanese self-defense martial art without weapons).
Famous for kodachijutsu are Chujo school and its branch, Tomita school.
In the Meiji era, the Imperial Japanese Army (IJA) established jukenjutsu, a Japanese style martial art using the bayonet (currently called jukendo) based on the Japanese traditional art of spearmanship,
In 1921, the IJA also established tankenjutu (the martial art using a short sword, currently called tankendo) based on kodachijutu at Army Toyama School, as a fighting style using a bayonet sword without being attached to the rifle part. Today, tankenjutu is played under the name of tankendo in Japanese martial arts, and because of its evolution from jukendo, the All Japan Jukendo Federation supervises tankendo.
Besides, self-defense arts or sports using techniques of kodachijutu include Sports Chanbara.