Ishii was born in Hirakata, Osaka and lived there during her early school years.
[1][2] She later moved to Tokyo, where she graduated from Waseda University and worked at a variety of part-time jobs, including department store salesperson and snack hostess, while writing stories in her free time.
[3][4] After almost winning a literary prize at age 33 she moved back to her parents' home in Osaka to try writing full-time.
[6] She made her literary debut at age 54 with her novel Hyakunen doro, about the aftermath of a once-in-a-century flood.
She has named Gabriel García Márquez and Yukio Mishima as two of her favorite authors.