The man generally credited with the origination of Iaido is Jinsuke Shigenobu (Hayashizaki), who lived through the Momoyama period when the three unifiers, Oda, Hideyoshi and Ieyasu conquered Japan. The art he founded between 1601 and 1615 is usually termed Shinmei Muso Ryu Batto Jutsu. He was later given the title of the first headmaster of the Muso Jikiden Eishin Ryu. From his teachings, several hundred schools of Iai were developed, of which some twenty or thirty are still extant.

The seventh headmaster of the Muso Jikiden Eishin line was a man named Hasegawa Chikaranosuke Eishin, who added to the school a set of tate hiza (raised knee) techniques usually called Eishin Ryu. Prior to this time, the school included techniques executed from both tate hiza and a standing position.

Omori Rokurozaemon Masamitsu was a student said to have been expelled from the school by Eishin at one time. Omori was a student of Ogasawara Buke Reiho, or etiquette, as well as the Shinkage school of sword. The Shinkage Ryu had a set of five Iai techniques called the Saya no Uchi Batto Gohan. Rokurozaemon developed a set of techniques, later called Omori Ryu, which were initiated from the formal seated posture called seiza. For this innovation (and probably an apology) Eishin re-admitted him to the school.

In the Taisho era (1912 - 1926), the seventeenth headmaster Oe Masamichi (Shikei) (1852 - 1927), incorporated the Omori waza as the introductory level. Shikei is the man who named the school Muso Jikiden Eishin Ryu and organised it into its present three-level system. These three sets of waza, Seiza no Bu (Omori Ryu), Tate Hiza no Bu (Eishin Ryu) and Oku Iai (Zawaza and Tach waza) along with several sets of partner practice (Tachi Uchi no Kurai and Tachi Ai no Kurie being the most common) and various leftover katas, total almost one hundred techniques in all.

At the time of the eleventh headmaster, the school had split into two lines, the Shimomura and the Tanimura. The Tanimura line became associated with the "common" folk, or the goshi farmer/warriors of Tosa prefecture, while the Shimomura stayed closer to the samurai classes in Koji, the capital. Both lines were quite secretive about their teachings when Nakayama Hakudo (1869 - 1958) was invited to Tosa from Edo.

Nakayama studied under teachers from both branches of the Muso Jikiden Eishin Ryu and is considered by some to be the last headmaster of the Shimomura ha. Eventually he developed a school of Iai which has become known as the Muso Shinden Ryu, now centered around Tokyo. It is Nakayama who popularised the name Iaido which appeared in 1932. The Muso Jikiden Eishin Ryu has since become more open and is practiced mainly in the West and South of Japan.

These two contemporaries, OE Masamichi and Nakayama Hakudo, are largely responsible for the survival and growth of Iaido in modern times. The two schools teach similar techniques, the katas differing in interpretation more than in fundamentals. The Muso Jikiden Eishin Ryu has eleven Omori Ryu techniques (with one variation which is seldom practised) while the Muso Shinden Ryu has added this variation to the set for a total of twelve. The names used for the individual waza are different for each school. At the Eishin Ryu and Oku Iai levels of training, both the names and numbers of techniques are the same. The Muso Shinden Ryu calls the three levels of practice Shoden (initiation), Chuden (intermediate) and Okuden (hidden or advanced).

The All Japan Kendo Federation (Zen Nihon Kendo Renmei) which is the largest governing body of Iaido schools, released a set of seven waza to be studied by kendo students. These techniques were developed by instructors from five different Iai schools and represented three seiza, one tate hiza and three standing kata. The set was named Sei Tei Gata which means roughly "representative forms". In 1980 three more standing waza were added.

Iaido - names of Kata

Schools from the Shinmei Muso Ryu