The gang discovers that the recent wave of earthquakes is connected to a phenomenon called poltergeisting - and there’s a chance Uiharu’s new roomie might be somehow be involved.

Kuroko suspects Haru'ue has something to do with the recent poltergeisting events, and it’s causing tension between her and Uiharu. Later, Haru'ue reveals a hidden part of her past.

The past comes into focus as Haru'ue and Edasaki’s connection to a common Child Error facility is revealed. Later, Misaka sets out to find Kiyama after learning that the rogue scientist is out on bail and working with the Frog Doctor.

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.

Rumors swirl about that Misaka is the template for a project to produce Level 5 clones. When Nunotaba refers to her as the "Original," Misaka decides to check her out, and learns that she worked at the hospital where Misaka submitted her DNA map.

In high spirits, Misaka joins the other girls for a day of shopping at Seventh Mist, where she helps the others with their shopping, as well. Misaka spends another day playing with children. One of Misaka's clones goes through the phases of her training.

Finding herself face-to-face with a clone of herself, Misaka ends up helping her get a cat out of a tree, sharing ice cream cones, and having tea with her. It isn't until later that Misaka discovers the true, sinister project that calls for her clones.

Misaka lashes out at Accelerator, but is left frustrated. She realizes the full breadth of the situation she has become involved in, and feels responsible for allowing it to happen. Nunotaba discusses the ramifacations of the clones' existence with Misaka.

With the end of summer vacation approaching, the girls plan a study session at Saten's apartment to catch up on homework. Everyone is to bring an ingredient for a potluck stew party, but most have trouble deciding what to buy, leading to some surprises.

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."

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.