1. A vehicle image display apparatus, comprising: a memory storing a program; and a processor configured to execute the program to: acquire a plurality of captured images of an area around a vehicle, the plurality of captured images being captured by a plurality of cameras that are mounted on the vehicle at a plurality of positions; generate a single image that includes a representation of the vehicle and a virtual viewpoint image of the area around the vehicle formed by combining the plurality of captured images such that a linear boundary region is formed between adjacent ones of the plurality of captured images extending from the representation of the vehicle to outer edges of the single image; display a composite image on a monitor after an input operation is given to an ignition switch of the vehicle, the composite image comprising: a first image including markings representing each linear boundary region in the single image, the first image superposed on the single image; and a second image including a plurality of markings, each of the plurality of markings spaced apart from an adjacent one of the plurality of markings, identifying a respective end region of the vehicle and having margins of a predetermined distance from an external surface of the vehicle in the representation of the vehicle, the second image superposed on the single image and the first image such that the plurality of markings of the second image is closer to the external surface of the vehicle in the representation of the vehicle than the markings of the first image; highlight the first and second images superposed on the single image for a time period after a start of display of the composite image; and change a level of highlighting of at least one of the first image or the second image after the time period has elapsed so that the second image has a greater level of highlighting than the first image after the time period elapses.