1. An information processing system comprising: a first feature; a second feature different from the first feature; and an information processing apparatus comprising: an image acquiring unit that acquires an image of a real space captured by an imaging device; a feature detection unit that detects one or more features from the image; an image generating unit that generates an image of a virtual space, by placing a virtual object made to correspond to the detected feature at a position based on the position of the feature in the virtual space; and a display control unit that causes an image to be displayed on a display device such that a user sees the virtual space image superimposed on a real space, wherein when the first feature and the second feature are detected in a real space image acquired by the image acquiring unit, the image generating unit places a first virtual object corresponding to the first feature in the virtual space at a position based on the position of the second feature.