Mieko grew up on the Windward side of Oahu, in the town of Kaneohe, where her father was a tenant farmer. She attended the Reverend Benjamin Parker School, the first school in the Windward district for grades 1-8, which opened in 1927. Upon completing the 8th Grade, Mieko attended sewing school, then worked in Honolulu as a domestic with her older sisters while they attended high school. During World War II, from 1942 through 1945, Mieko was a U.S. War Department civilian working as an aide at the Army hospital temporarily located on the grounds of the Territorial Hospital in Kaneohe. This hospital was one of several caring for servicemen wounded in the Pacific Theater and evacuated to Hawaii to recuperate. When the military hospital ceased operations in October 1945, Mieko resigned her position to remain in Kaneohe rather than relocate to Tripler General Hospital, which she deemed too far to commute from home. In recognition of her meritorious service, she was awarded a Certificate of Overseas War Service and an Overseas War Emblem in November 1945.
Post World War II, Mieko helped to raise and care for two generations of her nephews and nieces: Kenneth, John, Robert, and Claire Moritsugu; Beverly Nishikawa Knox and Alan Nishikawa; Anne Nakae Kuroda; Heidi Nagata Warren; and Greg and Tod Nishikawa; and great-nephews and great-nieces: Erika, Vikki and Emily Moritsugu; Michael Moritsugu; Ronald, Stephanie, and Kenneth Kuroda.; Kristin Knox Fratto, Kelly Knox, and Alex Taylor.
Her contributions to the growth and success of the generations that followed her are immeasurable.