The server device according to the invention includes: a storage unit that associates and stores multiple first characteristic data sets for each user and associates and stores second characteristic data for each group to which the multiple first characteristic data sets belong; a different-user-selecting unit that selects a different user when a predetermined event occurs while a game is being played; a group formation-assessing unit that determines whether or not all of the first characteristic data sets belonging to a group are included in the first characteristic data sets associated with the user and the different user; and an action-executing unit that executes predetermined actions using, in addition to the first characteristic data sets associated with the user and the different user, the second characteristic data associated with the group for which it has been determined that all of the pertinent first characteristic data sets are included.