1. An apparatus comprising: a memory storing instructions; and a control unit configured to execute the instructions to cause the apparatus to: detect a three-dimensional position and attitude of an object of interest within an image of real space, relative to a display image plane of the apparatus; and cause a display to display a modified image comprising an image of a modified object, corresponding to the object of interest, such that the modified object is displayed in an alignment parallel to the display image plane of the apparatus, wherein the display is caused to display the modified image by gradually changing the image of real space into the modified image through an animation, and wherein the modified object is a virtual object.