The Daihasei Festival.Academy City is hosting the Daihaisei Festival, a sports competition between the various schools of the city, during which visitors from outside the city are allowed entry. While Tōma's parents, Tōya Kamijō and Shiina Kamijō, as well as Misuzu Misaka, assumed to be Mikoto's older sister, get to know each other, Tōma and Mikoto decide to make a bet in which the loser does anything the winner wants. Meanwhile, Laura contacts Aleister Crowley to inform him that magicians have infiltrated Academy City in order to make a transaction with a magical weapon called the Stab Sword, which has the power to kill a Saint. Meanwhile, Tōma has several troubles with a hungry Index and awkward situations with the class representative, Seiri Fukiyose. Later, Tōma runs into Stiyl and Tsuchimikado, who tell him about the intruding magicians and asks him not to get Index involved. While getting scolded by Seiri after an awkward incident with Index and Komoe Tsukuyomi, Tōma runs into a woman named Oriana Thomson. When his Imagine Breaker reacts to her, he realizes she is one of the magicians in question and starts to follow her.