Keiko Nishi grew up in an area where teaching is one of the most respected careers. Manga was not allowed in the Nishi household, and Keiko was expected to become a teacher, like her father. During her study, a friend asks her to draw for the notorious magazine June, which specialized in homo-erotic stories. It was the first manga Nishi drew and the correspondence school's "headmistress", shoujo manga artist Keiko Takemiyashojo praised her work. In 1988, Keiko Nishi made her professional debut in the magazine Petit Flower.
After graduating, Keiko Nishi started teaching, but she quit after six months. Then she started drawing manga full-time, but didn't enjoy it. For Nishi, drawing manga was an outlet for frustration and stress. Ironically, her anthologies 'Gotta Become an Angel', 'I Wish I Was a Bird', 'When Water Turns to Ice', 'September', 'Another Ocean', 'Love Song', 'The Poor Princess', and 'Elevator Girl' are considered her most powerful work. It was not until 1993 that Nishi started to enjoy drawing manga. She drew 'The Beauty in the Hagiwara Shop in District Three' and 'The Rosemary Hotel: Vacancies Available'. Nishi has carved a niche for herself beyond standard genres, and she is sure to continue drawing for many years.