A scene is assigned to each page image, and an image included in the assigned scene is pasted on each page image. A page image addition instruction region is displayed between adjacent page images. In a case where the page image addition instruction region is clicked, a new page image is displayed between two page images between which the clicked page image addition instruction region is interposed. An image included in a scene assigned to a first page image of the two page images or a scene assigned to a second page image of the two page images is pasted on the new page image.