1. An information processing system, comprising: at least one hardware processor; and at least one hardware memory device that stores a plurality of instructions, which when executed by the at least one hardware processor, causes the at least one hardware processor to: determine whether or not a position within a virtual two-dimensional plane or a virtual three-dimensional space, where one of a first object and a second object is placed, is included in a determination region within the virtual two-dimensional plane or the virtual three-dimensional space that is set based on a position within the virtual two-dimensional plane or the virtual three-dimensional space where another one of the first object and the second object is placed, in a case where the first object is newly placed in the virtual two-dimensional plane or the virtual three-dimensional space based on a user's operation or in a case where the position of the first object is updated based on the user's operation; obtain a similarity degree between attribute information associated with the first object and attribute information associated with the second object, and determine whether the similarity degree is higher than a threshold; group the first object and the second object in a case where it is determined that the position within the virtual two-dimensional plane or the virtual three-dimensional space, where the one of the first object and the second object is placed, is included in the determination region that is set within the virtual two-dimensional plane or the virtual three-dimensional space and it is determined that the similarity degree is higher than the threshold; display a screen indicating a display target region of the virtual two-dimensional plane or the virtual three-dimensional space on each of a plurality of displays, the display target region being set in different positions for each of the plurality of displays; and place an advertisement object corresponding to the object group generated in an overlapping region of a plurality of display target regions respectively corresponding to the plurality of displays in a case where the object group is included in the overlapping region.