Mits Koshiyama was born on August 7, 1924 in Mountain View, California. With his parents, three brothers and three sisters he worked long hours on their leased strawberry farm in Santa Clara. He was about to graduate in June, 1942 when the family was shipped to the detention camp at the Santa Anita racetrack and then to Heart Mountain.
Koshiyama graduated high school inside Heart Mountain, and was 19 when he refused induction and joined the test case. He served his sentence on the honor farm at the federal penitentiary at McNeil Island, Washington.
After prison he rejoined his family, which was scraping by as strawberry sharecroppers. A friend allowed Koshiyama and a brother to enter the closely-guarded cut flower nursery business. Koshiyama got married in 1962 and put three children through college. After closing the nursery after 24 years, Koshiyama went to work as the landscape gardener at Willow Glen High School in San Jose. In 1989 students asked him to write an article for the school newspaper and Koshiyama began to speak in public about his wartime resistance.