Misaka 10031–10032 confusion

A confusion persists between the identities of Misaka 10031 and Misaka 10032 in the Toaru Majutsu no Index fandom. It originates most likely from the fact that Misaka 10031 did not identify herself when she was introduced to Misaka Mikoto and Kamijou Touma, moreover, was not even referred to her serial number, and later, Misaka 10032's sudden disappearance after Accelerator appeared before her.

Background
Misaka 10031 is first introduced to Kamijou Touma and Misaka Mikoto in a park near Vending Machine 7116, which Touma rationalizes maybe Mikoto's twin sister. Later, while carrying the strange juices that Mikoto got for him from the vending machine in question. Misaka 10032 appears to help him after he falls over with them. Here, it is literally pointed out by Misaka 10032 herself that she came from a different direction after Touma asks her about when Mikoto went away with her earlier in the day (Misaka 10031).

Later, Misaka 10032 disappears suddenly after Accelerator appears looking at her, and the experiment once again begins. After Touma discovers that Mikoto has clones and Misaka 10032 finally introduces herself to him, referring to herself as the Misaka that he had been contact. Since the experiment with Misaka 10032 occurs later that evening, the Misaka that died near the bookstore would be Misaka 10031.

Revelations
Despite this, the fandom's confusion persists years after the release of the novel and anime adaptation. It is not until a small omake drawn up for the manga showing the interactions of both timelines that it is shown explicitly their positions, unchallenged by the author moreover.

Furthermore, the fact that the clone that Mikoto chastized is blatantly spoiled out in the Railgun manga as Misaka 10031, and referred to her as getting her "big day" (being the 10031th experiment with Accelerator) on that day, and leaving the box of the black cat that Misaka 10032 would later come upon, leaves no doubt that the clone Touma and Mikoto met at the park was Misaka 10031.

Excerpts
