1. An information processing system, comprising: an attribute information storage unit that stores attribute information associated with each of a plurality of objects placed in a virtual two-dimensional plane or a virtual three-dimensional space; a determination unit that determines whether or not one of a first object and a second object different from the first object is included in a determination region that is set based on a position of another one of the first object and the second object 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; and a grouping unit that groups the first object and the second object based on a result of a comparison between the attribute information associated with the first object and the attribute information associated with the second object in a case where it is determined that the one of the first object and the second object is included in the determination region.