Ishisaka became one of the first wave of
aikidoka in the continental U.S.A. In 1964 he founded the Westminster Aikido School, and the first Aikido classes were held in the
Westminster high school. Soon after he moved to
Garden Grove, California where he launched the Orange County Aiki Kai in a larger facility. Ishisaka was the chief instructor of Orange County Aikikai for the remainder of his life. Koichi Tohei supported Ishisaka in founding the Orange County Aiki Kai
dojo. Ishisaka was one of Tohei's students who attended the first U.S. Ki Society organizational meeting at the
California State University, Fullerton, when Tohei was breaking away from the mainstream Aikikai organisation. For a period the school was affiliated with the Ki Society International, and Ishisaka was an associate lecturer with this organization. Later Ishisaka became independent of the Ki Society. Ishisaka was influential in the formation of Aikido societies in the
University of California, Irvine and the California State University, Fullerton, and in the introduction of Aikido instruction to the Orange County Department of Mental Health. He participated in various tournaments and exhibitions. He taught many pupils. Jerry Glassman, who founded the HAI KI Aiki Center in
Eugene, Oregon, was to accept honorary godan (5th dan) in 2000. Dan Kawakami, 6th
dan, is another pupil who went on to become a well-known instructor. Perhaps his best known pupil was
Steven Seagal, who began studying under Ishisaka as a teenager in the mid-1960s. A fellow student said "[Seagal] was crazy about Harry Ishisaka." Seagal continued to study at the Orange County Aikikai while making frequent visits to Japan where he studied under other masters, before moving to Japan in March 1973. While leading the OC Aikikai, Ishisaka also held a full-time job as a machinist with a company in
El Toro, California. He had risen to the rank of godan by the time of his death. Harry Ishisaka died in mid-January 1978 at the age of fifty, after suffering a heart attack during an Aikido demonstration at
Irvine College, California. OC Aikikai hosts an annual Harry Ishisaka memorial seminar. ==Philosophy==