Mikoto Misaka, one of the strongest Level 5 espers in Academy City, gave her DNA map to a certain doctor when she was young, believing that it may be used for greater good. Unfortunately for her, it ended up being used to create countless clones of herself; forming the Misaka network, in order to create the strongest esper by sacrificing these clones whom she considers as her own sisters.
Seiya was forced to accept an invitation to an amusement park by the mysterious and beautiful girl Isuzu. What he didn't know was that she would bring him to the decrepit Amagi Brilliant Park, Japan's most disappointing amusement park. Seiya is introduced to the leader of the Park, the "real princess" Latifah, who suddenly entrusts him with saving the park, which is in danger of shutting down. Amagi Brilliant Park, it turns out, is not just any amusement park, but rather one populated by fairies.
High school freshman Yuuta Togashi was once a "Chunibyo patient" i.e. an overly self-conscious middle schooler. He wants to bury this embarrassing past and begins a new life in high school unsuccessfully. His classmate Rikka Takanashi, a "current" chunibyo patient, has found traces of residual symptoms on him and used the fact to force Togashi "making a contract" with her.
In Oshima the happy, carefree 14-year-old Akane Isshiki lived a poor but well-loved life together with her reliable little sister, Momo, who does all the housework, and her grandfather, Kenjirō, a genius inventor who only created useless devices. When the weather is clear, they can see the artificial island, Blue Island, across the sea. In the center of that island rises the revolutionary Manifestation Engine, a discovery that solved the world's energy problems, and leads to some major problems.