The Founder of Iai-Do was the master swordsman Hayashizaki Jinsuke Shigenobu who lived around 1550 AD during the Muromachi Period. Most ancient schools of Iai-Do trace their roots back to this one man.

The Soke and Founder of Hokushin Shinoh Ryu, Shinoda OhHo Masatsune (1887-1976) studied swordsmanship with Hokushin Itto Ryu Kenjutsu and was a direct student of Soke Ono Nao Uemon. He remained with that school until the mid Meiji Era, where he received a Menkyo Kaiden, signifying mastery of all techniques.

A Menkyo Kaiden is a certificate issued to a student when the master believes he has taught his student everything he knows, conferring upon him full mastership of the art form. It is only at this point, that it becomes acceptable for a swordsman to study a different style from another master, any earlier would be considered disloyal.

Shinoda OhHo Masatsune then learned and mastered Shinto Ryu Kenjutsu under Soke Hibino Fu (1750) and also attained a Menkyo Kaiden in that style. He was granted permission by both Grand Masters to establish his own "Ryu", which he did by combining what he had learned from both schools' techniques.

In 1924, the 13th year of Emperor Taisho, Shinoda OhHo Masatsune founded Hokushin Shinoh Ryu Iai-Do in Kagoshima. In 1937, he also built and established a school (Honbu) in Nagoya, near to Tokugawa Castle. Shinoda named his school Hokushin Shinoh Ryu as a tribute to both of his teachers. Hokushin is from Hokushin Itto Ryu Kenjutsu, Shinoh uses the character Shin from Shinto Ryu Kenjutsu and the character Oh is from his own art-name OhHo.

The current Grand Master of Hokushin Shinoh Ryu, Kimura HekiHo and Master GoHo both have the character Ho in their Iai-Do art-names.
Hokushin Shinoh Ryu Iai-Do consists of twenty eight offensive and defensive movements (kata). Many of them start from the formal sitting position (seiza), rise through to the standing position and end by sheathing (noto) the sword while returning to the sitting position (seiza.) It is this distinctive flair that sets Koryu, Hokushin Shinoh Ryu Iai-Do apart from other schools of swordsmanship.

Iai-Do is the ancient Japanese art of drawing the sword and cutting in a single movement. It was created for the physical and mental discipline of the Samurai warrior.

Students are taught Iai-Do techniques for use against single and multiple attackers, even against spear (yari) and armour (yoroi). Iai-Do combines various offensive and defensive movements teaching a swordsman to receive and counter an attack from any direction.