Video game system and storage medium storing video game program

In response to a predetermined input operation by a player, item object initial information is produced. The item object initial information is information used for introducing an item object into a virtual game world and controlling the item object in the virtual game world. Then, the item object is introduced into the virtual game world, and controlled in the virtual game world according to a predetermined rule. The item object initial information is transmitted to other video game devices. Each of the other video game devices receives the item object initial information, based on which the video game device introduces the item object into the virtual game world and then controls the item object in the virtual game world according to a predetermined rule.