[1] She was the oldest of three children of a Japanese father (Shoji Osato, 1885–1955) and a Canadian mother of French-Irish origin (Frances Fitzpatrick, 1897–1954).

[3] She spent six years touring the United States, Europe, Australia and South America with the company, leaving in 1941 as she felt her career was stagnating.

[1][3] While at the ABT, she danced roles in such ballets as Kenneth MacMillan's Sleeping Beauty, Antony Tudor's Pillar of Fire, and Bronislava Nijinska's The Beloved.

[8][9] Following the Japanese attack on Pearl Harbor in 1941, Osato was encouraged to change her name to something more "American", and for a short time she used her mother's maiden name and performed as Sono Fitzpatrick.

[10] At around the same time, her father was arrested and detained in Chicago under the United States government's Japanese American Internment policy.