1. A non-transitory 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 comprising instructions configured to cause the computer to: acquire a first image; extract 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; display the first image at a first location on the display device; display a second image at a second location on the display device, where the first and second images are displayed at different, non-overlapping, locations on the display device; while the first image is displayed at the first location, acquire data of a coordinate input provided on the second image displayed at the second location on the display device; generate input position data representing a position of the coordinate input provided on the second image using the acquired data; superimpose a predetermined superimposition image on the first image to create superimposed first image, the predetermined superimposition image being superimposed at a position on the first image based on the first feature point, the position on the first image 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 update the first image displayed at the first location to be the superimposed first image, the superimposed first image being concurrently displayed with the second image.