The Reason I Jump is a work of nonfiction written by then-13-year-old Naoki Higashida about his experiences with autism. Through a series of questions and answers punctuated with other bits of insight and a short story that illustrates the isolation he feels, Higashida provides readers with a unique look into the mind of a person with autism.

The book opens with an introduction by David Mitchell, the father of a son with autism and the husband of the book's translator, KA Yoshida. Mitchell describes how the author wrote the book by spelling out words and sentences in his native Japanese on an alphabet grid. Mitchell expresses gratitude for this work because it has given him a greater understanding of his son and suggested ways to help him. The book also demonstrates that people with autism are just as bright and curious as everyone else.

Higashida explains that although he can read aloud and sing, he has difficulty conversing with people because his words disappear. Then, he proceeds to set up a series of questions that he answers with honesty and insight. Throughout the book, he expresses the frustration felt by people with autism stemming from their need to communicate effectively and the difficulty of doing so, along with their inability to control certain behaviors.

Examples of his explanations include the fact that he forgets things very quickly, which prompts him to repeat things over and over as a means of remembering what he has been told. The difficulty of finding the right words at the right time is one of the greatest challenges he faces, along with the uncontrollable, violent reaction he often has when the smallest things go wrong. Higashida explains many other facets of autism, including the gestures and vocal intonations people with autism often make, the reasons they wear the same clothing and eat the same foods repeatedly, and the reasons they are so attracted to nature and water. Throughout the book, the author laments the fact that he knows his behaviors are annoying to others and pleads for understanding and patience.

The book concludes with a short story called I'm Right Here. It is about a boy named Shun who is hit by a car, dies, and goes to heaven. His frustration at being invisible to his parents and unable to help them in their grief process mirrors the frustrations people with autism face as they try to communicate with others.