Mikoto Misaka is a famous girl in Academy City. Due to her being famous, she takes advantage of every guys affection. One day she flirts with the wrong guy and he forces Mikoto to drink a poison drug and then suddenly her female body turns into a boy. Will Mikoto gets her girl body back?

Mikoto Misaka has a younger adopted sister named Wendy and same goes with Kuroko Shirai has a step sister named Chelia when Shirai's mother died due to heart failure. But unexpected that both Wendy and Chelia have equal powers that their sisters did not know that they are not espers. Mikoto and Kuroko suddenly discovered that their sisters came from another magical portal outside Academy City.