1. A computer-readable storage medium having stored thereon an image processing program executed by a computer of an image processing apparatus that displays an image on a display device, the image processing program causing the computer to function as: first image acquisition means for acquiring a first image; first feature point extraction means for extracting at least a first feature point from the first image, the first feature point being a feature point having a first feature on the first image; second image display control means for displaying a second image on the display device; coordinate input acquisition means for acquiring data of a coordinate input provided on the second image displayed on the display device; input position data generation means for generating input position data representing a position of the coordinate input provided on the second image, using the data acquired by the coordinate input acquisition means; first image superimposition means for superimposing a predetermined superimposition image on the first image, at a position on the first image based on the first feature point, the position corresponding to a position, represented by the input position data, on the second image based on a second feature point, the second feature point being a feature point having the first feature on the second image; and first image display control means for displaying on the display device the first image on which the superimposition has been made by the first image superimposition means.