Yukiko Kai (, Kai Yukiko, 21 September 1954 - 12 December 1980) was a Japanese shà Âjo manga artist. Her real name was Kimiko Kaihatsu (, Kaihatsu Kimiko). She is considered a member of the Post Year 24 Group. Although she died young, her works are still analyzed. Manga artist Akiko Hatsu is her younger sister.
Born in Kanazawa, Ishikawa prefecture, Kai graduated from a high school and entered a company where she worked for one year. She joined the manga coterie magazine Ravuri which her friend Yasuko Sakata operated when she was in high school. In 1973, she went to Tokyo and became a manga assistant of Moto Hagio, and lived in Hagio's house. She also worked as an assistant of Keiko Takemiya.
Kai debuted in the Spring issue of Bessatsu Viva Princess (the first issue of this magazine) in Akita Shoten for her work Anasutashia no Sutekina Otonari (Nice Next-door Neighbor of Anastasia). She published the stories of the "Shiki series" (Seasons series) and the "Anastasia series" in the magazine Gekkan Princess and Bonita.
In 1979, when Moto Hagio, Aiko Ità Â, Yukiko Kai, Akiko Jà  and Shio Satà  visited the Europe, they participated in the 37th Worldcon, Seacon '79 at Brighton, United Kingdom.
After published Ryokuin KÃ Âro in the Summer issue of Bessatsu Viva Princess in 1980, Kai spent time under medical treatment at a hospital in Kanazawa city. She died on 12 December 1980 of stomach cancer at a hospital in Kanazawa.
The story which was contributed to the collaboration manga Kyà Âdai Jingi is her last work.
Kai read Japanese fantastic novels and works such as those by Tatsuhiko Shibusawa, Hideo Nakai () and Kunio Tsukamoto () etc. She was largely affected by these fantastic works. Kai wrote various genres of manga stories. But she loved Fantasy and Science fiction. Many of her works are classified in these genres.
There are nine books of Yukiko Kai published in Princess comics by Akita Shoten.
There are six bunkobon books of Yukiko Kai published by Akita Shoten. In this bunkobon version, even if the title of book is same as that of Princess comics version, the stories contained are different.