When a first user interface is chosen according to a choice instruction based on an operation input, a two-dimensional user interface object indicating an arrangement range of decorative items is displayed, and decorative items are disposed at locations in the range designated according to an operation input. When a second user interface is chosen, a three-dimensional user interface object indicating an arrangement range of decorative items is displayed, and decorative items are disposed at locations in the range designated according to an operation input. Types and arrangement of the decorative items on the two-dimensional object, or types and arrangement of the decorative items on the three-dimensional object, are stored into a storage medium according to a determination instruction based on an operation input.