Shimizu, who had a lung ailment, died Sunday at a Lakewood hospital, said Derrick Taylor, the Bellflower St. John Bosco coach with whom Shimizu continued to work.
Later Shimizu became a trusted assistant coach and advisor to Taylor at Woodland Hills Taft and St. John Bosco, staying in the background while offering sage advice.
"He's the most underrated, great high school coach in our era," Taylor said. "No one understood how good a coach and how brilliant a basketball mind he is."
When Taylor was coaching in the 2007 McDonald's All-American game and walked into a room for breakfast with Shimizu, a familiar voice spoke up: "Coach Shimizu."
It was John Wooden, the former UCLA coach. "That's when you know you're the man, when the ultimate coach calls you over," Taylor said.
A second-generation Japanese American, Shimizu was born Feb. 27, 1928, in Los Angeles. His family was caught up in the war hysteria after the Japanese attack on Pearl Harbor and sent to Wyoming as part of the internment of thousands of Japanese Americans on the West Coast.
The personable Shimizu talked about his family's interment with great reluctance.
"I know it's in the history books and it can't be erased. But it was a painful time, and I want to separate myself from the feelings," Shimizu said in a 1988 Times article.
He spent three years in Heart Mountain, Wyo., then returned briefly to Los Angeles before moving to suburban Ohio, where a teenage Shimizu used sports to break cultural barriers with his white teammates, The Times reported in 1988.
After graduating from high school, he returned to Los Angeles, where he earned a bachelor's degree from Cal State L.A. and began his career at Hamilton. He taught physical education and driver's education.
As a coach, Shimizu had a low-key reputation and preferred the "no-star system."
In the late 1980s, the 5-foot-5 Shimizu was still playing pickup games with his players, who raved about his defense. But they were forbidden to call him by his widely used nickname: "Shim."
"I've never gotten close to my players," Shimizu said in the 1988 interview. "I may ask guys to do things that are unpleasant in practice and I think it's easier to ask them if you're not buddy-buddy."
He is survived by two daughters and a son. Services are pending.