After bringing an end to World War III, Touma Kamijou disappears from the world. Both sides—magic and science—take the time to rest and regroup. While Accelerator spends his days with Last Order and Misaka Worst, Shiage Hamazura uses the secrets he gained in Russia as a bargaining chip and returns to Academy City to reform Team ITEM. It seems like peace is here at last. That is, until a new group called the Freshmen arrive...?