X²: Double X is a brief prequel, running for just two minutes and forty seconds, to the feature film X. It is one of four music videos, with the first three comprising of stills from CLAMP's X artwork prior to 1994, interspersed with live-action scenes. The fourth video is animated by Madhouse and is unique in that it contains a plot, introducing some key characters and summarizing the opening chapters of the X manga (equivalent to the first three episodes of the X TV series) that take place prior to the events of the main film.