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. At around the same time, her father was arrested and detained in Chicago under the United States government's Japanese American Internment policy. In 1942, when the Ballet Theatre toured Mexico, Osato was unable to join the tour as Japanese Americans were barred from leaving the country, and she had several months without work. She was also unable to perform in California and other parts of the western United States when the company toured there later in the same year, as these states were deemed military areas and were off-limits for people of Japanese descent.