A manager evaluation value setting unit sets a manager evaluation value indicating a management ability of a manager character to manage player characters. A player evaluation value setting unit sets a player evaluation value used to evaluate the player character according to an ability value indicating an ability of the player character. An evaluation difference value calculating unit calculates an evaluation difference value indicating a difference between the manager evaluation value and the player evaluation value when the manager evaluation value is lower than the player evaluation value. A management ability setting unit changes the manager evaluation value to reduce the management ability of the manager character as the evaluation difference value increases.