[3] Tsushima was born in Mitaka, Tokyo, the third child (younger of two daughters) of famed novelist Osamu Dazai and Michiko Ishihara, a teacher at a girls' school.
[4][5] Her father committed suicide when she was one year old;[6] she later drew on the aftermath of this experience in writing her short story "The Watery Realm".
[9] In 1972 her story Pregnant with a Fox (Kitsune wo haramu) was a runner-up for the Akutagawa Prize.
[11] In 1983 she was awarded the Kawabata Yasunari Literature Prize for her short story Danmari ichi (The Silent Traders),[12] and in 1986 she won the Yomiuri Prize for her novel Yoru no hikari ni owarete (Driven by the Light of the Night).
[21] Her stories, several of which draw on her own experience as a single mother,[20][22] focus on the psychological impact of abandonment on those left behind.