1. An image processing device comprising: circuitry configured as a superimposition display data storage unit which stores superimposition display data which is to be a source of an image that is superimposed on a visual field of a user; an environment map generating unit which generates an environment map representing a position of one or more objects existing in a real space based on an input image obtained by imaging the real space using an imaging device and feature data indicating a feature of appearance of the one or more objects; and an image superimposing unit which superimposes a superimposition display image on a visual field of the user, wherein in response to a selection of an item of a first layer of the superimposition display data by a foot of the user, the circuitry displays a second layer of the superimposition display data farther from the user on a floor surface than the first layer of the superimposition display data.