What is the theme in Number 9 Dream by David Mitchell?

Another theme is imagination and reality.A key idea throughout the novel is the merging of imagination and reality. As we can see in the beginning of the book, Eiji has an active imagination and is fond of creating his own reality. At the end of the book, as he realizes that the extent to which he has done this goes way beyond simple daydreams, we get the dizzying awareness that much of what we think of as objective reality is in fact subjective, created by us out of our own interpretations, emotions, and prejudices.