Mikoto and Kuroko get in trouble for using their powers in the dorm. Their punishment: pool cleaning duty! Later, Kuroko finds herself feeling frisky after accidentally ingesting a powerful aphrodisiac!

The Swim Club recruits Misaka and the gang to strut their stuff as swimsuit models! Later, after taking a break from posing and primping, the girls work together to make some curry.

The midsummer festival arrives, and students are preparing to show off their school for friends and family. Misaka’s scheduled to perform a violin solo for the festivities - if her nerves don’t get the best of her!

Therestina reveals new information about her real identity and her master plan. Meanwhile, Kuroko and the gang vow to fight alongside Misaka in order to save the children jeopardized by Therestina’s activities.

Misaka and her friends reach the facility where the children are being held, but Therestina uses Capacity Down to take the Espers out of the fight. With everything on the line, it’s up to Saten to save the day.

Haru'ue joins Saten and Uiharu on a trip to the Garden of Learning to see Misaka and Shirai, as well as to do some shopping. They later go to visit Edasaki in the hospital, where she is undergoing physical therapy, when things take an unexpected twist.

Edasaki is due to be discharged from the hospital, and it is learned that she will be living with Haru'ue. The move is bittersweet for Uiharu, who is losing her roommate, but she feels it is for the best. Meanwhile, a new movement is afoot in the city.

Febri takes an instant liking to Saten, and is warm to everyone except for Misaka, much to her chagrin. At Judgment, Uiharu is unable to find any information on who Febri is, so arrangements are made to admit her into an orphanage as a "Child Error."

As Yomikawa takes over investigating the runaway security robots, Konori invites the whole gang out to take in a bath at a bathhouse. On their way home, a number of detours lead them to a confrontation with yet another, much more dangerous runaway robot.

Therestina reluctantly provides Misaka with the clues she needs to find the group behind Febrie's secret. With Kongo's help, the girls identify Aritomi as the man they are pursuing, and find out more about him and his company, the STUDY Corporation.

Aritomi reveals his motivations for STUDY's project to Misaka. She also learns about Nunotaba's plight, and some of the details concerning what STUDY has planned at the Reach Assembly the next day. Will she be able to escape and put a stop them?

Shirai, Konori, Kongo and friends, and Uiharu and Saten confront the powered suits at the four Assembly sites, where they soon receive backup. Misaka and Febrie move to take on Aritomi directly, but he has one final surprise up his sleeve for them.