Misaka is the 10032nd clone of Misaka Mikoto, a Sister, that was first introduced in Toaru Majutsu no Index and plays a relatively small role in Toaru Kagaku no Railgun. Originally supposed to be killed in the 10032 experiment against Accelerator as part of the Level 6 Shift Project, she is one of the few Sisters that remained in Academy City for readjustments. She becomes the most prominent clone in the series after being rescued by Kamijou Touma, and is referred to as Misaka Imouto (御坂妹 Misaka Imōto?, lit. "Misaka's little sister") whenever they meet.