Kimiko Kasai's path into jazz began with a single radio broadcast: hearing Chris Connor sing "All About Ronnie" as a teenager in Kyoto convinced her this was the music she wanted to make. At sixteen she moved to Tokyo alone to pursue it, and by 1970 had recorded her debut as a leader, Just Friends.

What followed over the next decade is unusual even among this project's more internationally connected subjects: American jazz didn't treat her as a novelty crossover act. In 1971 she recorded two duo albums with pianist Mal Waldron, Left Alone and One for Lady — a stripped-down format that only works between musicians who trust each other completely. In 1972 came Satin Doll, a full album with the Gil Evans Orchestra, the arranger behind some of Miles Davis's most celebrated orchestral records. In Person followed in 1974 with Oliver Nelson, and Kimiko Is Here in 1975 with the Cedar Walton Trio — each a full album under her name, not a guest-vocal credit.

The record that made her internationally known came in 1979: Butterfly, recorded with Herbie Hancock and most of the Headhunters, plus Webster Lewis and Alphonse Mouzon. She and Hancock made a second album the same year, As / I Thought It Was You — two records with Herbie Hancock in a single year, evidence of a genuine working relationship rather than a one-off session.

She was married to producer Richard Rudolph, writer of "Lovin' You" and, before Kasai, the husband and producer of Minnie Riperton; Rudolph also produced records for Riperton, Teena Marie, and Kasai herself. By most secondary accounts she stepped away from the music business in the late 1980s to become a jewelry designer — her recorded catalog does thin to compilations and reissues from 1990 onward, consistent with that account, though it was not independently confirmed against a primary source on this pass.

Kasai's catalog moves fluidly between straight-ahead vocal jazz (the Mal Waldron duo records, the Gil Evans and Oliver Nelson orchestral dates) and the soul-jazz/fusion sound of her Herbie Hancock-era recordings, particularly Butterfly, which draws on the Headhunters' funk-inflected rhythm section rather than a conventional jazz combo.