The screenwriter of the film is Chihiro Ito, born in 1982. After watching "Spring Snow", Oshii Mamoru admired Ito's talent very much, and decided to invite her to join the love-centric "Sukai Kurora". Ito was surprised after receiving the invitation, but the animator's peaceful demeanor relieved her anxiety, and Oshii asked her to let her go to write. After fully studying the original work, Ito decided to make Suizo’s work on love the focus of the animation script, cutting into the story from her emotional expression, and gradually showing the fate of this special group of children.
There are six volumes of original novels. The film is mainly adapted from the first volume of "Sukai Kurora" published in 2001. However, from the perspective of time, this book depicts the last story that happened. Instead, the few books of the book explain the previous things. もりひろし revealed that this is his deliberate arrangement, and readers can start reading from any book.
