Yonamine died Monday at a Honolulu retirement home, said his son, Paul.
The outfielder was known as the "Nisei Jackie Robinson" for breaking into Japanese baseball and building ties between the countries in a sensitive period after World War II. Facing a language barrier, he was sometimes met with hostility for being an American and his aggressive style of play.
Yonamine, considered one of the greatest athletes to come out of Hawaii, was born in Olowalu, Maui, on June 24, 1925. His father was a sugar cane field worker from Okinawa. His mother was born on Maui.
Drafted into the Army after graduating from high school, Yonamine spent two years playing football and baseball while stationed at Schofield Barracks on Oahu. He played for the 49ers in 1947, three years before the team joined the National Football League.
He is believed to be the first player of Japanese ancestry to play pro football. Yonamine started three games with the 49ers, rushed 19 times for 74 yards, caught three passes for 40 yards and had intercepted a pass. But he was released after one season after injuring a wrist while playing baseball in the off-season.
Yonamine returned to baseball and played for the San Francisco Seals of the Pacific Coast League and the Salt Lake City Bees of the Frontier League before heading to Japan in 1951.
Yonamine played for the Yomiuri Giants and the Chunichi Dragons, helping transform how the game was played in Japan, where it was a more passive style of game then, with no players sliding hard into second base to break up a double play as Yonamine did in his first game, to the shock of fans.
With a .311 career batting average, the seven-time All-Star won three batting titles and was the 1957 Central League MVP before serving decades as a manager and being inducted into Japanese baseball's Hall of Fame in 1994.
Yonamine and his family later ran successful pearl stores in Tokyo and the Los Angeles area.
In 2007, the 49ers established the Perry/Yonamine Unity Award — named after former 49ers players Joe Perry and Yonamine — to recognize players who make a difference on the field and in the community.
In addition to his son, Yonamine is survived by his wife, Jane; and two daughters, Amy Roper and Wallis Yamamoto.