An operation method for an information processing device having a display area used to generate a video image projected into a projection target area by a projector is provided. The method includes: in a first mode for generating the video image, specifying a designated part designated by a user in the display area; displaying, in the display area, a first video image showing a first object arranged in the designated part and a second object which moves in the display area and changes on reaching the designated part; and causing the projector to project the first video image into the projection target area; and in a second mode for the projector to project the video image into the projection target area, causing the projector to project a second video image resulting from eliminating the first object from the first video image, as the video image into the projection target area.