Ai Kannazuki is a mysterious young man dispatched from the Prism World to serve as its final messenger. His principal objective is the elimination of Louis, a Rinne-type messenger also from the Prism World. His emergence occurs following the "PRISM.1" tournament, drawing him into events involving Shin Ichijo and the Septentrion unit. This arrival and mission are intrinsically tied to the ongoing conflicts among the messengers of the Prism World. His introduction further intersects with the appearances of characters from the Idol Time PriPara and Pretty Rhythm series, situating his role within the expansive narrative universe of the franchise.