Iaido (居合道 iaidō) is a sword-based Japanese martial art that trains the motions associated with drawing a katana(刀) from its sheath, striking an opponent, removing blood from the blade, and then re-sheathing the katana with smooth, controlled movement. Modern day exponents typically use iaito instead of shinken at least in beginning stages of study.

Iaido is often confused with both kendo(剣道) and battōjutsu (抜刀術 battōjutsu). While all three are martial arts involving the Japanese sword, they differ in focus. Iaido concerns itself primarily with drawing and sheathing the sword, while battojutsu focuses on cutting technique. Kendo, as an art, is interested in both drawing/sheathing and cutting, and adds a sporting aspect over the other two arts.

The primary emphasis is on the psychological state of being present. The secondary emphasis is on drawing the sword and attacking as quickly as possible. 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 iai, sometimes called the 'life of iai', is nukitsuke. This is a very quick draw accomplished by drawing the sword out of the saya(鞘) (scabbard) while drawing the saya itself back (saya biki). The blade can be brought out of the scabbard and used in a slashing motion very quickly using nukitsuke.

History
The Tenshin Shoden Katori Shinto-ryu included iaijutsu in its curriculum in 15th century, and first schools dedicated exclusively to sword drawing appeared some time during the late 16th or early 17th century. Most modern schools consider a samurai called Hayashizaki Jinsuke Minamoto no Shigenobu (1546-1621) as the originator of iaido. Not much is known about his life, and some scholars doubt his existence as a historical figure. The two largest schools of iaido that are practised today, Muso Shinden-ryu and Muso Jikiden Eishin-ryu, both claim a lineage starting with Hayashizaki.

While not a hard and fast rule, frequently the word iaido is used to refer to the modern self improvement oriented form taught by the All Japan Kendo Federation (AJKF) and other iaido associations while iaijutsu is used for the older, combative techniques of the koryu. The word iaido itself was coined by Nakayama Hakudo (1873?-1958) in early 20th century. Before that various other names like battō, battōjutsu, or saya no uchi were used instead.


Styles of iaido
The term "iaido" can include many styles of Japanese swordsmanship, "all of which subscribe to non-combative aims and purposes."


Zen Nippon Kendo Renmei Iai
An Iaido Division was formed within The All Japan Kendo Federation (AJKF) in 1956. In 1969, the AJKF introduced the Seitei Gata curriculum of seven kata (techniques or forms) for iaido(全日本剣道連盟居合). These seitei gata,or seitei iai, were drawn from several of the major traditional sword schools.

In 1980 three more kata were added and then two more in 2000, thus increasing the seitei iaido (seitei gata) curriculum to the current twelve.

These twelve seitei gata are now standardised for the tuition, promotion and propagation of iaido and as a result, seitei iaido has since become the most widely recognised form of iaido in Japan and the rest of the world.


Main classical styles of iaido
The two main classical styles (koryu) of iaido practised worldwide are Muso Jikiden Eishin-ryu and Muso Shinden-ryu. They resemble each other quite strongly because they branched off from one style sometime in the 18th century, under Oguro Motouemon Kiyakatsu sensei. Instead of one sōke (headmaster), two of his students continued Oguro's teaching by creating Muso Jikiden Eishin ryū (Hayashi Masanoju Masamori) and Muso Shinden ryū (Matsuyoshi Tadesuke Hisanari). One of the differences between the two schools can be seen in the noto (sheathing the katana back in the saya). In Muso Shinden, noto is done on the horizontal plane, the blade parallel to the floor. In Jikiden, the blade is perpendicular to the floor in a more or less vertical plane.

There are several branches of Muso Jikiden Eishin-ryū (MJER) that are practised today. Different Iaido organisations generally recognise different people as their sōke. One person who is considered to be a sōke is Miura Takeyuki Hidefusa, who holds a 9th Dan in MJER. The All Japan Iaido Federation (Dai Nippon Iaido Renmei) recognises Ajisai Hirai (9th Dan Hanshi) as the 22nd sōke of MJER.

There are several lines of transmission extant for Muso Shinden-ryu also. One of them claims Mitsuzuka Takeshi as the sōke, second one (those who are affiliated with Nippon Iaido Kyokai) regard Takada Gakudō as their head teacher.

In the ZNKR federation (Zen Nihon Kendo Renmei, one of the largest federation both in Japan and outside Japan)　there are two lines representing the Muso school. The current sōke for Muso Jikiden Eishin-ryū is Fukui Torao (21st master), and the last sōke for Muso Shinden -ryū was Nakayama Hakudo with no official successor.


Modern iaijutsu
A newer style of iaijutsu is Toyama-ryu battōjutsu. This is a style originating in the late 19th century, and taught primarily to officers in the Second World War. It is different from the older styles primarily in that all techniques are performed from a standing position. Neither the older styles nor Toyama-ryu can be said to be more effective, however, it has been a long time since swordsmen of differing schools fought with 'Shinken' (sharp/live blades).