1. A non-transitory computer readable medium storing an image processing program that is executed by a computer which displays a synthesized image of a real world image and a virtual image on a display device, the image processing program causing the computer to execute: acquiring a real world image captured by a real camera; generating a synthesized image by synthesizing the real world image and a virtual image depicting a first virtual object, in such a manner that the first virtual object appears to be present behind the real world image; and displaying the synthesized image on the display device.