From old times IAI (pronounced e-i) has evolved connected with the refinements of sword making, and its trend has been at the center of Japan's historical Martial Arts. The Iai tradition, passed on from generation to generation, received its widest growth through the creative hand of one Hayashizaki Jinsuke Shigenobu, about 400 years ago. Born in the old province of Oshu, Shigenobu prayed at the Hayashizaki Myôjin Shrine in Tateoka-Chô, Yamagata Prefecture. By revelation he awakened to an exquisite truth about the very nature of Iai. He systematized Iai as an independent Bujutsu (martial art), and named it Hayashizaki Ryu, or Shigenobu Ryu. Since his death he is revered as the founder and creative genius of Iai. From that period hence the art has flourished within a multitude of traditional schools, of which some twenty-five remain today.
There are still many different Ryu-Ha or traditional schools. Among the most practiced are: the Muso Shinden Ryu, the Muso Jikiden Eishin Ryu, the Tamiya Ryu, the Hoki Ryu, the Shinkage Ryu and the Katori Shinto Ryu. A lifetime of study would not permit mastering of all these styles. Therefore, it may be beneficial for students of the sword arts to learn the essentials of each school in synthesized forms and thus understand the basic techniques, especially the art of drawing the sword. In 1968 and 1977 two special commissions composed by eleven masters associated with the Zen Nihon Kendo Renmei (All Japan Kendo Federation) combined the basic techniques of the various Ryu-Ha into seven, later ten, and nowadays twelve “Kata” forms. These twelve Kata contain the fundamental essence of Iai. Additional insight can be gained through intensive training within the old Ryu-Ha, where the spirit of the art is manifested.