In male dominated Japan, Okamoto had to fight against sexism. She had a supervisor sympathetic to women in science during the early stages of her career.
However she and a coworker were asked to leave a pediatric conference, because the event was not for "women and children"  (onna kodomo), a term she said in a 2012 interview she had never heard before.
After she had presented her research for the first time, the male audience members ridiculed her by asking if she was going to dance for them.
In the video interview, Okamoto said: "Men are always aware of the fundamental differences between men and women, and so cannot help but think of themselves as superior. So I used that to my advantage by stroking their egos. [...] Until [I had a child] I could compensate for the disadvantages of being a woman by working longer hours—10 hours per day instead of the 8 that the men worked." At Keio University, she could not find day care for her daughter and brought her to the laboratory, "[hoping] that she would behave herself". She carried her on her back as an infant while working in the lab.