Earning the rank of first-degree black belt at age 14, Imamura would eventually attain the rank of Kudan, or ninth degree, 60 years later in 2007. Between these benchmarks, he positively influenced thousands of people in the Valley, the United States, and around the world as a competitor and a coach. As a member of the All-Japan Collegiate team touring the United States in 1955, he visited the Valley and after graduating from Tenri University decided to continue studies at Fresno City College in 1958.

​Two years later, he won the prestigious title of Grand Champion – the best out of all weight classes – at the AAU Senior National Tournament, with future U. S. Senator Ben Campbell of Colorado among his opponents. Imamura repeated as 180-pound AAU champion in 1960. in 1976, Imamura began a U. S. – Japan judo exchange program which provided high school judoists the opportunity to compete in cities such as Tokyo and Hiroshima. Through the years, judoists from both countries have benefited from their overseas experiences.

Imumura, who became a kinesiology professor at the university in 1980, coached the Fresno State men’s club team to national titles in 1985 and 1988. In 1989, his Bulldogs women’s team shared the national crown with San Jose State. Among his national collegiate individual champions were sons Rodney, Richard and Randy, and all four of his sons attained black belt.

​Throughout the 1980s and 1990s, Imamura served as the U. S. National Judo coach and traveled the world leading his pupils. In 2002, he began taking junior-high school teams to an annual international tournament in Japan, competing against countries such as Russia, South Korea, Germany, South Africa, Taiwan, Egypt, and Japan. At the grassroots level, he coached clubs in Fresno, Clovis and Reedley.

California Judo named Imamura the Coach of the Year in 2006. Imamura, it has been said, “epitomizes the judo creed of maximum, efficient use of mind and body to perfect oneself and contribute to the welfare of self and to mankind.”