Academy City is a highly developed place in terms of technology. It is said to be 20 to 30 years ahead of the rest of the world. Eighty percent of its 2.3 million residents are students. The focus of studies here is directed towards esper powers. Misaka Mikoto, one of the top level espers in town, shares a room with Kuroko Shirai, another high level esper who is a member of Judgement, a law enforcing agency composed of students. Both attend to Tokiwadai, a private school reserved for the high-leveled and the rich. Kuroko's partner at Judgement, Kazari Uiharu, is a low level esper who studies at Sakugawa middle school. Her best friend and classmate there is Ruiko Saten, a level zero (no esper powers). Together, the four encounter several adventures in the exciting scientific town.
Eruna Ichinomiya is a third-year junior high school student who has not decided on which high school to attend, and spends her days skipping school and playing games at home. One day, Eruna's eyes are captivated by a photo of Seisa Mikagura in a pamphlet for Mikagura Private Academy, given to her by her cousin, Shigure Ninomiya. Feeling that it is fate, Eruna decides to attend Mikagura Academy. However, Eruna discovers that Mikagura Academy is a school where only cultural clubs exist, and that it has an intense battle system where students with special powers must fight each other as representatives of their own clubs.
With just five students (none in the same grade ), the four girls of the tiny Asahioka Branch School still enjoy watching cherry blossoms, playing in rivers, digging potato, and building igloos together. The pace is very slow yet enjoyable and heartwarming.