Kazuko was born in Tokyo as a first daughter of Eisuke Yoshiyuki, a writer, and Aguri.

A lifelong sufferer of asthma since she was two years old, she was frequently taken as a child to Okayama, where her grandparents lived, for a change of air.

She started her career as an actress with theatre troupe Gekidan Mingei in 1955, appearing in the role of Sophie in Junji Kinoshita's A Japanese Called Otto in 1966.

Her major breakthrough on the stage came when she played Anne Frank in The Diary of a Young Girl in 1977.

She won Best Supporting Actress award in 1959 Mainichi Film Award, then won Best Actress in 1978 Japan Academy Prize for her role in the film Empire of Passion.