On a display screen, a game image including a plurality of target images and a game character image is displayed. The target images moves so as to pass over the game character image. When an input is provided from a player onto a touch panel, input coordinates are detected. In response, display coordinates of each target image at the time of the input are detected. When display coordinates located within a predetermined range from the input coordinates are present, specified coordinates are determined based on at least one of a position represented by display coordinates and a position represented by the input coordinates. The game character has characteristic parameters which are varied in accordance with a positional relation between the specified coordinates and the game character image.