After World War II and the Second Sino-Japanese War respectively in 1945, she moved to Keio University in Shinanomachi in Tokyo. As resources were scarce, she and her husband Shosuke Okamoto changed to research on blood: "If there was not enough we could simply use our own". They hoped to find a treatment for post-partum haemorrhage, a potent drug to stop bleeding after childbirth. They began by studying epsilon-amino-caproic acid (EACA). They then studied a related chemical, 1-(aminomethyl)-cyclohexane-4-carboxylic acid (AMCHA), also known as tranexamic acid. The Okamotos found it was 27 times as powerful and thus a promising hemostatic agent and published their findings in the Keio Journal of Medicine in 1962.
