Game management device, game system, and computer-readable storage medium having program recorded thereon

A game management device which manages a game includes a prior registration unit for setting a registered character, according to an information on an operation of selecting a prescribed number of characters from the characters owned by the user when the operation is performed by a prescribed time limit; a real event accepting unit for accepting an information on a real event produced by the existent object after the prescribed time limit; and a game information change unit for changing, when it is determined that the existent object corresponding to the registered character produced a prescribed real event, a user's game information to offer a reward or a disadvantage on a basis of the information on the real event accepted by the real event accepting unit.