In ancient times, a little girl named Eva, living in a primitive tribe, accidentally discovers that the paintbrush she carries has incredible power—as long as she draws something, the moment the final stroke falls, the thing in the drawing may truly appear in the real world. During a wolf attack, a panicked Eva unintentionally creates "fire" with the paintbrush and discovers that wolves fear flames. Under the protection and help of a hunter named Owen, she and her tribespeople learn for the first time to use torches to drive away wild beasts, and a little wolf is also taken in by her as a result. From then on, Eva realizes that this paintbrush may be able to change everyone's life.
But after all, Eva is just a naive and imaginative little girl, and her creations are never successful on the first try. To save a feverish tribesperson, she mishears a description and draws a giant man-eating flower; to let her people eat their fill, she draws fruit and meat, only to accidentally discover that meat becomes more fragrant after falling into fire; when a rainstorm comes and the worn-out tent cannot keep out the rain, she goes from "patching the roof" through repeated trial and error and finally creates a truly sturdy wooden house. After that, more and more new things continue to appear, such as blankets, dolls, shoes, clothes, stilts, and weapons. Again and again, Eva makes jokes because of wrong sizes, functions, or misunderstandings, and again and again she revises them.