Her father, Hirota Ritarô [ja] was a successful engineer who received his education and training at the Tokyo Imperial University.

This experience resulted in Katō and her husband suffering from a breakdown of health, which prompted the couple to move to the United States in 1919.

[3] Katō began to live a more independent life as her husband went off to Washington, D.C., to act as a consultant and interpreter for the Japanese delegation to a conference of the International Labor Organization.

[2] It was during this time that Katō began to socialize with the socialist acquaintances of her husband, which eventually led her to meet Margaret Sanger.

[2] On her return to Japan in 1921, Katō continued to strive for economic independence, and began her mission to propagate birth control education.

[2] The right-wing pro-natalist Japanese government arrested Katō in 1937 for her promotion of "dangerous thoughts," specifically her advocacy of birth control and abortion rights, and she spent two weeks in prison.

[1] In 1946 she wrote concerning the link between the birth control movement and Japanese democracy:Giving birth to many, and letting many die—repeating such an unwise way of life for Japanese women will result in exhaustion of the maternal body, as well as mental damage and material loss for the family.… Without the liberation and improvement of women, it is impossible to build democracy in Japan.

Katō championed many causes during this time, including birth control legislation, the abolition of the feudal family code, the establishment of the Women's and Minors Bureau of the Department of Labor, and environmental issues.

[5] She was also helped to establish the Family Planning Federation of Japan, which works to achieve "a society where everyone in the country can have access to voluntary reproductive health services".

In an obituary at the Web site of the International Planned Parenthood Federation, the writer noted that her efforts "have continued to bear fruits for Japanese society, bringing down the number of abortions, infant mortality, and maternal death rates, while increasing contraceptive usage to 80 percent.