Koretoshi Maruyama is the founder of Aikido Yuishinkai International.

Born 1936 he studied economics at Keio University where, after many years of studying other martial arts including judo, wrestling and boxing, he found in Aikido what he had been searching for over many years: a martial art that did not depend on strength, and that taught correct attitude of mind.

In 1972 Maruyama Sensei joined the Ki Society as the Chief Instructor, travelling extensively around the world to promote Aikido and becoming president in 1990. In 1991, after resigning from his position in the Ki Society, he undertook a 10 year period of seclusion in a temple in Saitama Prefecture, emerging in 2001. Receiving permission from the temple priest, he established Aikido Yuishinkai International in 1996, appointing Michael Williams as its chief instructor.

With Aikido Yuishinkai, Maruyama Sensei returns to the Aikido taught to him by the art's founder Morihei Ueshiba, emphasising the relationship with Daito Ryu and with the Shinkage Ryu sword school. It also includes yuki, or healing with ki.