In the book "Bugei Ryuha Daijiten" by Watatani Kiyoshi and Yamada Tadashi, Hayashizaki Jinsuke (Minamoto no) Shigenobu is credited with establishing the influence and popularity of iaidō, early in the sixteenth century. However, around a century before his birth, the dynamic art of iaijutsu had been developed by Iizasa Ienao, the founder of the Tenshin Shōden Katori Shintō-ryū.
Iaido should not be confused with kendo
or kenjutsu:
Kendo teaching does not include
drawing and re-sheathing of a sword. The
main weapon used in kendo, a flexible
bamboo sword (shinai), uses no
scabbard. Kendo is practiced with a
partner in full contact training or in
forms (kata) practice.
Kenjutsu is generally practiced
with a partner, in the form of
predetermined routines, and often does
include drawing or resheathing of the
sword.
Delineation from battōjutsu, literally meaning "technique of drawing the sword" is more difficult: battōjutsu is the historical (ca. 15th century) term encompassing both the practice of drawing the sword and cutting (tameshigiri). The term iaijutsu (居合術) became prevalent later (ca. 17th century), and the current term iaidō is due to the general trend (stemming from gendai budō) to replace the suffix -jutsu with -dō in Japanese martial arts in order to emphasize a philosophical or spiritual component. In contemporary usage, battōjutsu focuses on the techniques of cutting, with individual practice that starts with the sword in the sheath.
Iaidō forms (kata) are performed individually against one or more imaginary opponents. Some traditional iaido schools, however, include kata performed in pairs. Some styles and schools also do not practice tameshigiri, cutting techniques.
The primary emphasis in iaido is on the psychological state of being present (居). The secondary emphasis is on drawing the sword and responding to the sudden attack as quickly as possible (合). Starting positions can be from combative postures or from everyday sitting or standing positions. The ability to react quickly from different starting positions was considered essential for a samurai (侍).
A very important part of iaido, is nukitsuke or the life of iai. This is a very quick draw accomplished by drawing the sword out of the saya by moving the saya back in saya biki. The blade may be brought out of the saya and used in a quick nukitsuke slashing motion.
