[2] His work contributed to deeper collaboration between the AAU and the USJF.
[5] In 1965, he became the head of the National AAU Judo Committee, replacing Philip S. Porter (who was later a USJA founder).
[7] In 1970, he was listed in Black Belt magazine's hall of fame.
[9] For a period, Koiwai was a critic of the United States Judo Association, which he felt did not follow the rules of the federation.
[10] He was a close friend of judo pioneer Yosh Uchida.