Keiko Nagita, born November 28, 1949 in Tokyo, is a Japanese writer known for her extensive work in manga, novels, poetry, and essays. She is recognized for writing under several pen names, most notably Kyoko Mizuki, as well as Ayako Kazu and Akane Kouda. Before establishing her writing career, she spent time as an actress with the Shiki Theatre Company during her late teens.

Nagita began her professional writing journey at a young age, selling her first short story when she was 19 years old and deciding to become a full-time writer. In the 1970s, she wrote numerous stories for shōjo manga magazines such as Shōjo Friend and Nakayoshi under her various pen names. Her most famous work is the manga series Candy Candy, which she wrote as Kyoko Mizuki with artwork by Yumiko Igarashi. The series, which began in 1975, follows an orphaned girl named Candice White and became a major success. It was adapted into a 115-episode anime television series by Toei Animation in 1976 and later into several anime films. For this work, she and Igarashi won the Kodansha Manga Award for Best Shōjo Manga in 1977.

Beyond Candy Candy, Nagita created numerous other manga stories. These include Greenhill Monogatari (1970-1971) with artist Yasuko Aoike, Lorient no Aoi Sora (1974-1975) with Yoko Shima, Byakuya no Nightingale (1976-1977) also with Yoko Shima, and Premier Muguet (1979-1981) with Yoko Hanabusa. She continued writing manga later in her career, producing Loreley in 2008 with artist Kaya Tachibana, marking her return to the medium after an 18-year hiatus.

The specific work mentioned by the user, Shampoo Ōji, is a picture book series written by Nagita as Keiko Nagita with art by Makoto Kubota. The series was adapted into an anime television series that began airing in October 2007.

Beginning around 1980, Nagita shifted her focus primarily to writing juvenile fiction and love stories for young girls under her real name, Keiko Nagita. Her Fūko to Yūrei series became particularly popular. Her short story Akai Mi Haziketa was included in a Japanese primary school textbook for sixth grade published by Mitsumura Tosho. In 2007, she won the Japan Juvenile Writers Association Prize for Rainette, Kin Iro no Ringo, a novel about a Japanese girl and a Belarusian boy affected by the Chernobyl nuclear disaster.

Recurring themes in Nagita's work often draw from Western literature, with Lucy Maud Montgomery's Anne of Green Gables being a notable influence on her writing. Her personal experiences, particularly the loss of her father at age 12 and her mother when she was 21, shaped the emotional depth of her storytelling. She has stated that writing Candy Candy helped heal the sorrow of losing her parents and that the theme of accepting one's destiny regardless of parentage was central to the story.

Nagita's significance in the industry includes her legal battle over the rights to Candy Candy. In the 1990s, a dispute arose with illustrator Yumiko Igarashi over the ownership of the series. Supported by her publisher Kodansha, Nagita was confirmed in 2001 as the original author of the story. As a result of this dispute, she has since chosen not to authorize reprints of the Candy Candy manga. She continues to write, and lives with her husband and daughter, with the family maintaining a cottage on Prince Edward Island in Canada.