The Daihasei Festival is under way and the prestigious Tokiwadai Middle School, where the Ace of Tokiwadai, Mikoto Misaka reside, is one of the schools participating in this annual sports fest. However, not all are fun and games as people behind the shadows start to plot a new threat that will endanger Mikoto and the whole Academy City. After the Daihasei Festival, Mikoto and her friends find themselves being involved in multiple incidents surrounding special cards that supposedly record people's dreams.