(Chronology: Daihaseisai Arc of A Certain Magical Index.) The Daihaseisai is here! A festival event where all the schools in Academy City compete with each other in sporting events.. a festival even more popular then the World Cup. Espers from all over are encouraged to use their abilities. Meanwhile, the Board of Directors have taken an interest in Ben Tennyson after his success in defeating the Eigth Level 5 Impulser.. the Level 5 whose power was impossible to categorize.. and Aleister Crowley, the City administrator has taken up a rather sinister plan to find out how to test this new weapon in his arsenal... attract the most powerful conquerer in the Galaxy to do battle with that boy.
Meanwhile, Ben is starting to realize the possibility that he might have feelings for Mikoto, but is scared of what it might mean... And while Mikoto feels the same way, she doesn't know what to do with those feelings..
But of course.. all things must eventually converge and resolve, for better or for worse.