Koiwai was the former head of the United States Judo Federation. ^[1] Koiwai was the former head of the United States Olympic Committee and the past chairman of the National AAU Judo Committee. ^[2] He would work for both the AAU and the USJF to work together. ^[3] In 1960 he would write the Official A.A.U. - J.B.B.F. Judo Handbook. ^[4] In 1965 he would become the head of the National AAU Judo Committee replacing later USJA founder Phil Porter. ^[5] Koiwai would commission a study on injuries in Judo. ^[6] He earned his medical degree from Hanhehamm Medical College in 1947. ^[7] He would specialize in pathology. ^[8] For a period Koiwai was a critic of the United States Judo Association, whom he felt didn't follow the rules of the federation. ^[9] He would pass away on February 23, 2009. ^[10] Services were held in Pennsylvania. ^[11]