I found this information on a website about all jitsu arts Ancient system of combat based on jujutsu; founded by Shinra SaburoYoshimitsu during the Kamakura period (1185 - 1336) in Japan. Also known as aiki-jujutsu, it is the art from which aikido has developed. Sometime during the 13th century, a school existed to the north of Mt. Fuji that specialised in the teaching of aiki-jutsu. It was kept secret except to a few disciples, for the most part Japanese nobles of ancient lineage. This art had originated from Kenjutsu. The term aiki, like ju, indicates a principle, a way of using the body as a weapon of combat. The method of aiki is to use the the co-coordinated power of ki in harmony with the circumstances of combat; by blending one’s strategy with an opponent’s, to attain full control over him and over the encounter. Hope it helps