An example game apparatus determines, when an input has been made with a cross button, whether an input direction indicates a diagonal direction. When the input direction indicates a diagonal direction, a follow parameter is set such that a virtual stick vector is changed so as to slowly approach an input vector. When the input direction does not indicate a diagonal direction, the follow parameter is set such that the virtual stick vector is changed so as to approach the input vector fast. Further, the game apparatus calculates the follow parameter according to an inner product of the virtual stick vector and the input vector. The game apparatus updates the virtual stick vector based on the virtual stick vector having been most recently obtained, the input vector, and the follow parameter.