She was the first woman to be appointed as the President of the Physical Society of Japan and the first Japanese student to have studied at Keele University in Staffordshire, United Kingdom.

Her father died in New Guinea battle during Second World War when she was 5; and her mother, Toshiko, who became the main breadwinner of her family, supporting two young children, Fumiko and her baby sister, and her grandmother.

Yonezawa spent her early career in Kyoto and Tokyo where she published her work on Coherent Potential Approximation (CPA).

After her family moved back to Japan in 1976, Yonezawa was appointed Associate Professor at the Yukawa Institute of Theoretical Physics at Kyoto University.

The company policy didn't allow spouses to accompany them, so Fumiko visited the British Council in Kyoto and wrote a letter to 30 vice-chancellors of universities in the UK asking for a scholarship to study in graduate school.